Here are two ways to include HTML5 elements in your WordPress post content without WordPress’ wpautop function wrapping them in p tags or littering your code with line breaks.

HTML5 has several new elements that you may want to use in your post content to markup document sections, headers, footers, pullquotes, figures, or groups of headings. One way to safely include these elements in your posts is simple; the other way is a bit more complicated. Both ways rely on hand-coding the HTML5 markup in the WordPress editor’s HTML view.

If you are adding HTML5 elements to your post content then you should use an HTML5 doctype.

Disable wpautop for your theme

This is the simple way. Disable the wpautop function so that WordPress makes no attempt to correct your markup and leaves you to hand-code every line of your posts. If you want total control over every line of your HTML then this is the option for you.

To disable wpautop entirely add these lines to your theme’s functions.php:

remove_filter('the_excerpt', 'wpautop');
remove_filter('the_content', 'wpautop');

However, wpautop is generally quite useful if most of your posts are simple text content and you only occasionally want to include HTML5 elements. Therefore, modifying wpautop to recognise HTML5 elements might be more practical.

Modify wpautop to recognise HTML5 elements

WordPress’ wpautop is part of the core functions and can be found in this file within your WordPress installation: wp-includes/formatting.php. It controls how and where paragraphs and line breaks are inserted in excerpts and post content.

In order to create a modified version of WordPress’ core wpautop function I started off by duplicating it in my theme’s functions.php file.

What I’ve experimented with is disabling wpautop and adding a modified copy of it – which includes HTML5 elements in its arrayss – to my theme’s functions.php file.

Add the following to your theme’s functions.php file and you’ll be able to use section, article, aside, header, footer, hgroup, figure, details, figcaption, and summary in your post content. (Probably best to try this in a testing environment first!)

/* -----------------------------
MODIFIED WPAUTOP - Allow HTML5 block elements in wordpress posts
----------------------------- */

function html5autop($pee, $br = 1) {
   if ( trim($pee) === '' )
      return '';
   $pee = $pee . "
"; // just to make things a little easier, pad the end
   $pee = preg_replace('|<br />s*<br />|', "

", $pee);
   // Space things out a little
    // *insertion* of section|article|aside|header|footer|hgroup|figure|details|figcaption|summary
   $allblocks = '(?:table|thead|tfoot|caption|col|colgroup|tbody|tr|td|th|div|dl|dd|dt|ul|ol|li|pre|select|form|map|area|blockquote|address|math|style|input|p|h[1-6]|hr|fieldset|legend|section|article|aside|header|footer|hgroup|figure|details|figcaption|summary)';
   $pee = preg_replace('!(<' . $allblocks . '[^>]*>)!', "
$1", $pee);
   $pee = preg_replace('!(</' . $allblocks . '>)!', "$1

", $pee);
   $pee = str_replace(array("
", "
"), "
", $pee); // cross-platform newlines
   if ( strpos($pee, '<object') !== false ) {
      $pee = preg_replace('|s*<param([^>]*)>s*|', "<param$1>", $pee); // no pee inside object/embed
      $pee = preg_replace('|s*</embed>s*|', '</embed>', $pee);
   }
   $pee = preg_replace("/

+/", "

", $pee); // take care of duplicates
// make paragraphs, including one at the end
   $pees = preg_split('/
s*
/', $pee, -1, PREG_SPLIT_NO_EMPTY);
   $pee = '';
   foreach ( $pees as $tinkle )
      $pee .= '<p>' . trim($tinkle, "
") . "</p>
";
   $pee = preg_replace('|<p>s*</p>|', '', $pee); // under certain strange conditions it could create a P of entirely whitespace
// *insertion* of section|article|aside
   $pee = preg_replace('!<p>([^<]+)</(div|address|form|section|article|aside)>!', "<p>$1</p></$2>", $pee);
   $pee = preg_replace('!<p>s*(</?' . $allblocks . '[^>]*>)s*</p>!', "$1", $pee); // don't pee all over a tag
   $pee = preg_replace("|<p>(<li.+?)</p>|", "$1", $pee); // problem with nested lists
   $pee = preg_replace('|<p><blockquote([^>]*)>|i', "<blockquote$1><p>", $pee);
   $pee = str_replace('</blockquote></p>', '</p></blockquote>', $pee);
   $pee = preg_replace('!<p>s*(</?' . $allblocks . '[^>]*>)!', "$1", $pee);
   $pee = preg_replace('!(</?' . $allblocks . '[^>]*>)s*</p>!', "$1", $pee);
   if ($br) {
      $pee = preg_replace_callback('/<(script|style).*?</\1>/s', create_function('$matches', 'return str_replace("
", "<WPPreserveNewline />", $matches[0]);'), $pee);
      $pee = preg_replace('|(?<!<br />)s*
|', "<br />
", $pee); // optionally make line breaks
      $pee = str_replace('<WPPreserveNewline />', "
", $pee);
   }
   $pee = preg_replace('!(</?' . $allblocks . '[^>]*>)s*<br />!', "$1", $pee);
// *insertion* of img|figcaption|summary
   $pee = preg_replace('!<br />(s*</?(?:p|li|div|dl|dd|dt|th|pre|td|ul|ol|img|figcaption|summary)[^>]*>)!', '$1', $pee);
   if (strpos($pee, '<pre') !== false)
      $pee = preg_replace_callback('!(<pre[^>]*>)(.*?)</pre>!is', 'clean_pre', $pee );
   $pee = preg_replace( "|
</p>$|", '</p>', $pee );

   return $pee;
}

// remove the original wpautop function
remove_filter('the_excerpt', 'wpautop');
remove_filter('the_content', 'wpautop');

// add our new html5autop function
add_filter('the_excerpt', 'html5autop');
add_filter('the_content', 'html5autop');

The results are not absolutely perfect but then neither is the original wpautop function. Certain ways of formatting the code will result in unwanted trailing </p> tags or a missing opening <p> tags.

For example, to insert a figure with caption into a post you should avoid adding the figcaption on a new line because an image or link appearing before the figcaption will end up with a trailing </p>.

<!-- this turns out ok -->
<figure>
  <a href="#"><img src="image.jpg" alt="" /></a><figcaption>A figure caption for your reading pleasure</figcaption>
</figure>

<!-- this turns out not so ok -->
<figure>
  <a href="#"><img src="image.jpg" alt="" /></a>
  <figcaption>A figure caption for your reading pleasure</figcaption>
</figure>

Another example would be when beginning the contents of an aside with a paragraph. You’ll have to leave a blank line between the opening aside tag and the first paragraph.

<aside>

This content could be a pullquote or information that is tangentially related to the surrounding content. But to get it wrapped in a paragraph you have to leave those blank lines either side of it before the tags.

</aside>

Room for improvement

Obviously there are still a few issues with this because if you format your post content in certain ways then you can end up with invalid HTML, even if it doesn’t actually affect the rendering of the page. But it seems to be pretty close!

Leave a comment or email me if you are using this function and find there that are instances where it breaks down. I ran numerous tests and formatting variations to try and iron out as many problems as possible but it’s unlikely that I tried or spotted everything.

Hopefully someone with more PHP and WordPress experience will be able to improve upon what I’ve been experimenting with, or find a simpler and more elegant solution that retains the useful wpautop functionality while allowing for the use of HTML5 elements in posts. Please share anything you find!

This is an experiment that creates social media icons using CSS and semantic HTML. It uses progressive enhancement to turn an unordered list of text links into a set of icons without the use of images or JavaScript.

Demo: Pure CSS social media icons

Support: Firefox 3.5+, Safari 4+, Chrome 4+, Opera 10+, IE8+.

CSS social media icons

The image below shows you the final appearance in modern browsers.

This experiment starts with a simple list of links, with each link using meaningful text, and then progressively styles each link to take on the appearance of the relevant social media icon. As a result, there should be support for screenreaders or users with CSS disabled.

I’ve also included basic text in the title attribute of each link to provide information for users who may not be familiar with what service a specific icon represents.

This is an experiment that uses CSS 2.1 and CSS3 that is not supported by Internet Explorer 6 and 7, therefore, you shouldn’t expect it to work in those browsers. CSS is not necessarily the most appropriate tool for this kind of thing either.

Example code

The technique I’ve used is much the same as the one used for the Pure CSS speech bubbles.

The HTML is just a basic unordered list of links to various social networking websites or services.

<ul>
   <li class="facebook"><a href="#non" title="Share on Facebook">Facebook</a></li>
   <li class="twitter"><a href="#non" title="Share on Twitter">Twitter</a></li>
   <li class="rss"><a href="#non" title="Subscribe to the RSS feed">RSS</a></li>
   <li class="flickr"><a href="#non" title="Share on Flickr">Flickr</a></li>
   <li class="delicious"><a href="#non" title="Bookmark on Delicious">Delicious</a></li>
   <li class="linkedin"><a href="#non" title="Share on LinkedIn">LinkedIn</a></li>
   <li class="google"><a href="#non" title="Bookmark with Google">Google</a></li>
   <li class="orkut"><a href="#non" title="Share on Orkut">Orkut</a></li>
   <li class="technorati"><a href="#non" title="Add to Technorati">Technorati</a></li>
   <li class="netvibes"><a href="#non" title="Add to NetVibes">NetVibes</a></li>
</ul>

I’ve applied some general styles to the elements that make up this list.

ul {
   list-style:none;
   padding:0;
   margin:0;
   overflow:hidden;
   font:0.875em/1 Arial, sans-serif;
}

ul li {
   float:left;
   width:66px;
   height:66px;
   margin:20px 20px 0 0;
}

ul li a {
   display:block;
   width:64px;
   height:64px;
   overflow:hidden;
   border:1px solid transparent;
   line-height:64px;
   text-decoration:none;
   /* css3 */
   text-shadow:0 -1px 0 rgba(0,0,0,0.5);
   -moz-border-radius:5px;
   -webkit-border-radius:5px;
   border-radius:5px; /* standards version last */
}

ul li a:hover,
ul li a:focus,
ul li a:active {
   opacity:0.8;
   border-color:#000;
}

Each icon uses it’s own set of styles. This is the CSS that created the RSS icon.

.rss a {
   position:relative;
   width:60px;
   padding:0 2px;
   border-color:#ea6635;
   text-transform:lowercase;
   text-indent:-186px;
   font-size:64px;
   font-weight:bold;
   color:#fff;
   background:#e36443;

   /* css3 */
   -moz-box-shadow:0 0 4px rgba(0,0,0,0.4);
   -webkit-box-shadow:0 0 4px rgba(0,0,0,0.4);
   box-shadow:0 0 4px rgba(0,0,0,0.4);
   background:-webkit-gradient(linear, left top, left bottom, from(#f19242), to(#e36443));
   background:-moz-linear-gradient(top, #f19242, #e36443);
   background:linear-gradient(top, #f19242, #e36443);
}

.rss a:before,
.rss a:after {
   content:"";
   position:absolute;
   bottom:10px;
   left:10px;
}

/* create circle */
.rss a:before {
   width:12px;
   height:12px;
   background:#fff;
   /* css3 */
   -moz-border-radius:12px;
   -webkit-border-radius:12px;
   border-radius:12px;
}

/* create the two arcs */
.rss a:after {
   width:22px;
   height:22px;
   border-style:double;
   border-width:24px 24px 0 0;
   border-color:#fff;
   /* css3 */
   -moz-border-radius:0 50px 0 0;
   -webkit-border-radius:0 50px 0 0;
   border-radius:0 50px 0 0;
}

Acknowledgements

This post was inspired by an experiment on insicdesigns that producing a few social media icons using CSS.

An experiment that uses pseudo-elements to create 84 simple GUI icons using CSS and semantic HTML. Shared as an exercise in creative problem solving and working within constraints. This is not a “production ready” CSS icon set.

Demo: Pure CSS GUI icons

Known support: Firefox 3.5+, Safari 5+, Chrome 5+, Opera 10.6+.

An exercise in constraint

Several months ago I was experimenting with the creation of common GUI icons with CSS. The HTML is very simple and it relies on CSS pseudo-elements rather than extraneous HTML elements. The technical aspects of this exercise might be of interest to others, so I’ve decided to share it.

Pseudo-elements provide many possibilities to developers interested in enhancing existing semantic HTML.

Example code

The technique behind this experiment is an expansion of the basic shape-creation that was used to make Pure CSS speech bubbles. Some of these GUI icons can only be created in browsers that support CSS3 transforms.

The HTML is a basic unordered list of links.

<ul>
  <li class="power"><a href="#non">Power</a></li>
  <li class="play"><a href="#non">Play</a></li>
  <li class="stop"><a href="#non">Stop</a></li>
  <li class="pause"><a href="#non">Pause</a></li>
</ul>

Each icon uses its own set of styles. For example, the key parts of the CSS responsible for the “expand” icon are as follows:

.expand a:before {
  content: "";
  position: absolute;
  top: 50%;
  left: 1px;
  width: 5px;
  height: 0;
  border-width: 7px 7px 0;
  border-style: solid;
  border-color: transparent #c55500;
  margin-top: -4px;
  /* css3 */
  -webkit-transform: rotate(-45deg);
  -moz-transform: rotate(-45deg);
  -o-transform: rotate(-45deg);
  transform: rotate(-45deg);
}

.expand a:after {
  content: "";
  position: absolute;
  top: 50%;
  left: 5px;
  width: 8px;
  height: 8px;
  border-width: 3px 0 0 3px;
  border-style: solid;
  border-color: #c55500;
  margin-top: -6px;
}

.expand a:hover:before,
.expand a:focus:before,
.expand a:active:before {
  border-color: transparent #730800;
}

.expand a:hover:after,
.expand a:focus:after,
.expand a:active:after {
  border-color: #730800;
}

The demo page contains a full set of user interaction and media player control icons, as well as other common icons. For now, several icons actually require more than one element as CSS 2.1 only specifies 2 pseudo-elements per element that can contain generated content. The CSS3 Generated and Replaced Content Module allows for an unlimited number of pseudo-elements but has yet to be fully implemented in any modern browser.

Create a simple CSS folded-corner effect without images or extra markup. It works well in all modern browsers and is best suited to designs with simple colour backgrounds.

Demo: Pure CSS folded-corner effect

Known support: Firefox 3.5+, Chrome 4+, Safari 4+, Opera 10+, IE 8+

This post is going to expand on the technique used to create the folded-corner effect that is part of the demo page for Multiple Backgrounds and Borders with CSS 2.1. As a starting point it will look to recreate the appearance of the note style used on the Yiibu‘s fantastic web site. Where Yiibu uses images, this will use pseudo-elements.

Nothing complicated. Any element will do and there’s no need for extra markup. It’s just a simple coloured box to start with. Browsers with no support for pseudo-elements, such as IE6 and IE7, will only be capable of displaying this.

Adding position:relative makes it possible to absolutely position the pseudo-element.

.note {
  position: relative;
  width: 30%;
  padding: 1em 1.5em;
  margin: 2em auto;
  color: #fff;
  background: #97C02F;
}

The folded-corner

The folded-corner is created from a pseudo-element that is positioned in the top corner of the box. The pseudo-element has no width or height but is given a thick border. Varying the size of the border will vary the size of the folded-corner.

In this example, the top and right borders are set to colours that match the background colour of the box’s parent. The left and bottom border are then given a slightly darker or lighter shade of the box’s background colour.

.note:before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  border-width: 0 16px 16px 0;
  border-style: solid;
  border-color: #658E15 #fff;
}

This is all that’s needed to create a simple folded-corner effect like that found on Yiibu.

Firefox 3.0 doesn’t allow for the positioning of pseudo-elements. You can throw in a couple of extra styles to help tidy things up in that browser.

.note:before {
  ...
  display: block;
  width: 0;
}

Adding a subtle shadow

The appearance of a fold can be slightly enhanced by adding a box-shadow (for browsers that support it) to the pseudo-element. Setting overflow:hidden on the note itself will help hide parts of the shadow that would disrupt the folded-corner effect.

.note:before {
  ...
  -webkit-box-shadow: 0 1px 1px rgba(0,0,0,0.3), -1px 1px 1px rgba(0,0,0,0.2);
  -moz-box-shadow: 0 1px 1px rgba(0,0,0,0.3), -1px 1px 1px rgba(0,0,0,0.2);
  box-shadow: 0 1px 1px rgba(0,0,0,0.3), -1px 1px 1px rgba(0,0,0,0.2);
}

Rounded corners

It’s also relatively simple to make this work with rounded corners if desired. Unfortunately, every modern browser has some form of border-radius bug – including those using the non-prefixed property – which means a slight work around is needed.

Webkit browsers are the only browsers that can come anywhere close to rounding the corner of the pseudo-element if it only has 2 borders. Opera 11 and Firefox 3.6 make a mess of it. Opera 11 makes the biggest mess.

Using 4 borders avoids the problems in Opera 11 and Firefox 3.6. But it will trigger a bug in Safari 5 that leaves the diagonal looking a little jaggy. We can get around this problem by setting at least one border colour to be transparent.

When a background colour is applied to the pseudo-element it will show through the transparent border. Ideally, this approach would form the basis of the entire effect because we could reduce the amount of code needed. But Opera 11 will not show the background colour through the transparent borders unless a border-radius has been set.

.note-rounded:before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  border-width: 8px;
  border-color: #fff #fff transparent transparent;
  background: #658E15;
  -moz-border-radius: 0 0 0 5px;
  border-radius: 0 0 0 5px;
  display: block;
  width: 0;
}

The CSS file on the demo page has more comments on the work arounds. Every browser has its own peculiarities when it comes to using border-radius or borders on elements with no width or height. This is the merely simplest solution I’ve found to deal with those browser inconsistencies.

The final code

This is all the CSS needed to create a simple folded-corner effect, with a subtle shadow, from a single HTML element. To include a variant with rounded corners, the “note” object can be extended with the modifications described previously.

.note {
  position: relative;
  width: 30%;
  padding: 1em 1.5em;
  margin: 2em auto;
  color: #fff;
  background: #97C02F;
  overflow: hidden;
}

.note:before {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  border-width: 0 16px 16px 0;
  border-style: solid;
  border-color: #fff #fff #658E15 #658E15;
  background: #658E15;
  -webkit-box-shadow: 0 1px 1px rgba(0,0,0,0.3), -1px 1px 1px rgba(0,0,0,0.2);
  -moz-box-shadow: 0 1px 1px rgba(0,0,0,0.3), -1px 1px 1px rgba(0,0,0,0.2);
  box-shadow: 0 1px 1px rgba(0,0,0,0.3), -1px 1px 1px rgba(0,0,0,0.2);
  /* Firefox 3.0 damage limitation */
  display: block; width: 0;
}

.note.rounded {
  -moz-border-radius: 5px 0 5px 5px;
  border-radius: 5px 0 5px 5px;
}

.note.rounded:before {
  border-width: 8px;
  border-color: #fff #fff transparent transparent;
  -moz-border-radius: 0 0 0 5px;
  border-radius: 0 0 0 5px;
}

The demo page shows the final effect, an example with rounded corners, and how different coloured notes are easy to create from this base.

This technique works less well when the element receiving the folded-corner effect is sitting on top of a background image rather than a simple background colour. However, the same limitation exists for image-based methods of creating this effect.

Research into improving the cross-browser consistency of both the “clearfix” and “overflow:hidden” methods of containing floats. The aim is to work around several bugs in IE6 and IE7.

This article introduces a new hack (with caveats) that can benefit the “clearfix” methods and the new block formatting context (NBFC) methods (e.g. using overflow:hidden) of containing floats. It’s one outcome of a collaboration between Nicolas Gallagher (that’s me) and Jonathan Neal.

If you are not familiar with the history and underlying principles behind methods of containing floats, I recommend that you have a read of Easy clearing (2004), Everything you know about clearfix is wrong (2010), and Clearfix reloaded and overflow:hidden demystified (2010).

Consistent float containment methods

The code is show below and documented in this GitHub gist. Found an improvement or flaw? Please fork the gist or leave a comment.

Micro clearfix hack: Firefox 3.5+, Safari 4+, Chrome, Opera 9+, IE 6+

.cf {
  /* for IE 6/7 */
  *zoom: expression(this.runtimeStyle.zoom="1", this.appendChild(document.createElement("br")).style.cssText="clear:both;font:0/0 serif");
  /* non-JS fallback */
  *zoom: 1;
}

.cf:before,
.cf:after {
  content: "";
  display: table;
}

.cf:after {
  clear: both;
}

Overflow hack (NBFC): Firefox 2+, Safari 2+, Chrome, Opera 9+, IE 6+

.nbfc {
  overflow: hidden;
  /* for IE 6/7 */
  *zoom: expression(this.runtimeStyle.zoom="1", this.appendChild(document.createElement("br")).style.cssText="clear:both;font:0/0 serif");
  /* non-JS fallback */
  *zoom: 1;
}

The GitHub gist also contains another variant of the clearfix method for modern browsers (based on Thierry Koblentz’s work). It provides greater visual consistency (avoiding edge-case bugs) for even older versions of Firefox.

The only difference from existing float-containment methods is the inclusion of a CSS expression that inserts a clearing line-break in IE 6 and IE 7. Jonathan and I found that it helps to resolve some of the visual rendering differences that exist between these browsers and more modern ones. First I’ll explain what some of those differences are and when they occur.

Containing floats in IE 6/7

In IE 6 and IE 7, the most common and robust method of containing floats within an element is to give it “layout” (find out more: On having Layout). Triggering “layout” on an element in IE 6/7 creates a new block formatting context (NBFC). However, certain IE bugs mean that previous float containment methods don’t result in cross-browser consistency. Specifically, this is what to expect in IE 6/7 when creating a NBFC:

1. The top- and bottom-margins of non-floated child elements are contained within the ancestor element that has been given “layout”. (Also expected in other browsers when creating a NBFC)
2. The bottom-margins of any right-floated descendants are contained within the ancestor. (Also expected in other browsers when creating a NBFC)
3. The bottom-margins of any left-floated children are not contained within the ancestor. The margin has no effect on the height of the ancestor and is truncated, having no affect outside of the ancestor either. (IE 6/7 bug)
4. In IE 6, if the right edge of the margin-box of a left-floated child is within 2px of the left edge of the content-box of its NBFC ancestor, the float’s bottom margin reappears and is contained within the parent. (IE 6 bug)
5. Unwanted white-space can appear at the bottom of a float-container. (IE 6/7 bug)

There is a lack of consistency between IE 6/7 and other browsers, and between IE 6 and IE 7. Thanks to Matthew Lein for his comment that directed me to this IE 6/7 behaviour. It was also recently mentioned by “Suzy” in a comment on Perishable Press.

IE 6/7’s truncation of the bottom-margin of left-floats is not exposed in many of the test-cases used to demonstrate CSS float containment techniques. Using an IE-only CSS expression helps to correct this bug.

The CSS expression

Including the much maligned <br style="clear:both"> at the bottom of the float-container, as well as creating a NBFC, resolved all these inconsistencies in IE 6/7. Doing so prevents those browsers from collapsing (or truncating) top- and bottom-margins of descendant elements.

Jonathan suggested inserting the clearing line-break in IE 6/7 only, using CSS expressions applied to fictional CSS properties. The CSS expression is the result of many iterations, tests, and suggestions. It runs only once, the first time an element receives the associated classname.

*zoom: expression(this.runtimeStyle.zoom="1", this.appendChild(document.createElement("br")).style.cssText="clear:both;font:0/0 serif");

It is applied to zoom, which is already being used to help contain floats in IE 6/7, and the use of the runtimeStyle object ensures that the expression is replaced once it has been run. The addition of font:0/0 serif prevents the occasional appearance of white-space at the bottom of a float-container. And the * hack ensures that only IE 6 and IE 7 parse the rule.

It’s worth noting that IE 6 and IE 7 parse almost any string used as CSS property. An earlier iteration used the entirely fictitious properties “-ms-inject” or “-ie-x” property to exploit this IE behaviour.

*-ie-x: expression(this.x||(this.innerHTML+='<br style="clear:both;font:0/0">',this.x=1));

However, this expression is evaluated over and over again. Using runtimeStyle instead avoids this. Sergey Chikuyonok also pointed out that using innerHTML destroys existing HTML elements that may event handlers attached to them. By using document.createElement and appendChild you can insert the new element without removing all the events attached to other descendant elements.

Containing floats in more modern browsers

There are two popular methods to contain floats in modern browsers. Creating a new block formatting context (as is done in IE 6/7 when hasLayout is triggered) or using a variant of the “clearfix” hack.

Creating a NBFC results in an element containing any floated children, and will prevent top- and bottom-margin collapse of non-floated children. When combined with the enhanced IE 6/7 containment method, it results in consistent cross-browser float containment.

The other method, known as “clearfix”, traditionally used a single :after pseudo-element to clear floats in a similar fashion to a structural, clearing HTML line-break. However, to prevent the top-margins of non-floats from collapsing into the margins of their float-containing ancestor, you also need to use the :before pseudo-element. This is the approach taken in Thierry Koblentz’s “clearfix reloaded”. In contemporary browsers, the micro clearfix hack is also suitable.

The method presented in this article should help improve the results of cross-browser float containment, whether you predominantly use “clearfix” or the NBFC method. The specific limitations of both the “clearfix” and various NBFC methods (as outlined in Thierry’s articles) remain.

Problems

Using a CSS expression to change the DOM in IE 6/7 creates problems of its own. Obviously, the DOM in IE 6/7 is now different to the DOM in other browsers. This affects any JavaScript DOM manipulation that may depend on :last-child or appending new children.

This is still an experimental work-in-progress that is primarily research-driven rather than seeking to become a practical snippet of production code. Any feedback, further testing, and further experimentation from others would be much appreciated.

Thanks to these people for contributing improvements: Jonathan Neal, Mathias Bynens, Sergey Chikuyonok, and Thierry Koblentz.

Applying conditional classnames to the html element is a popular way to help target specific versions of IE with CSS fixes. It was first described by Paul Irish and is a feature of the HTML5 Boilerplate. Despite all its benefits, there are still a couple of niggling issues. Here are some hacky variants that side-step those issues.

An article by Paul Irish, Conditional stylesheets vs CSS hacks? Answer: Neither!, first proposed that conditional comments be used on the opening html tag to help target legacy versions of IE with CSS fixes. Since its inclusion in the HTML5 Boilerplate project, contributors have further refined the technique.

However, there are still some niggling issues with the “classic” conditional comments approach, which Mathias Bynens summarized in a recent article on safe CSS hacks.

1. The Compatibility View icon is displayed in IE8 and IE9 if you are not setting the X-UA-Compatible header in a server config.
2. The character encoding declaration might not be fully contained within the first 1024 bytes of the HTML document if you need to include several attributes on each version of the opening html tag (e.g. Facebook xmlns junk).

You can read more about the related discussions in issue #286 and issue #378 at the HTML5 Boilerplate GitHub repository.

The “bubble up” conditional comments method

Although not necessarily recommended, it looks like both of these issues can be avoided with a bit of trickery. You can create an uncommented opening html tag upon which any shared attributes (so no class attribute) can be set. The conditional classes are then assigned in a second html tag that appears after the <meta http-equiv="X-UA-Compatible"> tag in the document. The classes will “bubble up” to the uncommented tag.

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta http-equiv="X-UA-Compatible"
          content="IE=edge,chrome=1">
    <meta charset="utf-8">
    <!--[if lt IE 7]><html class="no-js ie6"><![endif]-->
    <!--[if IE 7]><html class="no-js ie7"><![endif]-->
    <!--[if IE 8]><html class="no-js ie8"><![endif]-->
    <!--[if gt IE 8]><!--><html class="no-js"><!--<![endif]-->

    <title>Document</title>
  </head>
  <body>
  </body>
</html>

Fork the Gist

The result is that IE8 and IE9 won’t ignore the <meta http-equiv="X-UA-Compatible"> tag, the Compatibility View icon will not be displayed, and the amount of repeated code is reduced. Obviously, including a second html tag in the head isn’t pretty or valid HTML.

If you’re using a server-side config to set the X-UA-Compatible header (instead of the meta tag), then you can still benefit from the DRYer nature of using two opening html tags and it isn’t necessary to include the conditional comments in the head of the document. However, you might still want to do so if you risk not containing the character encoding declaration within the first 1024 bytes of the document.

<!DOCTYPE html>
<html lang="en">
<!--[if lt IE 7]><html class="no-js ie6"><![endif]-->
<!--[if IE 7]><html class="no-js ie7"><![endif]-->
<!--[if IE 8]><html class="no-js ie8"><![endif]-->
<!--[if gt IE 8]><!--><html class="no-js"><!--<![endif]-->
  <head>
    <meta charset="utf-8">
    <title>Document</title>
  </head>
  <body>
  </body>
</html>

Fork the Gist

The “preemptive” conditional comments method

Another method to prevent the Compatibility View icon from showing was found by Julien Wajsberg. It relies on including a conditional comment before the DOCTYPE. Doing this seems to help IE recognise the <meta http-equiv="X-UA-Compatible"> tag. This method isn’t as DRY and doesn’t have the character encoding declaration as high up in the document, but it also doesn’t use 2 opening html elements.

<!--[if IE]><![endif]-->
<!DOCTYPE html>
<!--[if lt IE 7]><html class="no-js ie6"><![endif]-->
<!--[if IE 7]><html class="no-js ie7"><![endif]-->
<!--[if IE 8]><html class="no-js ie8"><![endif]-->
<!--[if gt IE 8]><!--><html class="no-js"><!--<![endif]-->
  <head>
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <meta charset="utf-8">
    <title>Document</title>
  </head>
  <body>
  </body>
</html>

Fork the Gist

While it’s interesting to explore these possibilities, the “classic” method is still generally the most understandable. It doesn’t create invalid HTML, doesn’t risk throwing IE into quirks mode, and you won’t have a problem with the Compatibility View icon if you use a server-side config.

If you find any other approaches, or problems with those posted here, please leave a comment but also consider adding what you’ve found to the relevant issues in the HTML5 Boilerplate GitHub repository.

Thanks to Paul Irish for feedback and suggestions.

I recently moved from London to San Francisco to work at Twitter, as a Software Engineer. This is a rough guide – in the spirit of @chanian’s tutorial for Canadians – based on my experience of relocating, the mistakes I made along the way, and some information I wish I’d had. Use it at your own risk – don’t assume any legal truths; research things for yourself before making decisions!

I’m not going to cover anything about the US visa process. The company that has offered you employment in the US is likely to work with immigration lawyers who will handle (or guide you through) the visa application and processing. I’m also going to assume that your employer is providing temporary accommodation or that you are organising your own (e.g., via Airbnb) while you search for an apartment. Most of this article relates to things you will need to do once you arrive in San Francisco and soon after, but that you should spend some time thinking about beforehand.

Get a phone

You’ll need a US mobile/cell number pretty quickly, especially if you’re apartment-hunting.

The US telecom market isn’t great and will leave you nostalgic for the halcyon days of the EU-regulated, pro-consumer market you’ve left behind. For example, it’s now illegal to unlock a phone from a carrier unless you have that carrier’s permission to do so. Furthermore, if you do get a phone from a carrier (as part of your contract deal), you should be aware of whether or not you will be locked into a proprietary network, like Verison’s CDMA. Without a US credit history, you should expect to pay a sizable deposit when entering into a contract.

One way to reduce the cost of a phone contract is to bring your own phone to the party. If you bring a phone from the UK, make sure to check that your charger will work on US voltage. With an unlocked, GSM-supporting phone you can look to carriers like T-Mobile who offer various “value” and no-annual-contract plans. These prices are significantly cheaper because they don’t subsidise the purchase of a new phone. You’re likely to find “unlimited” data plans easier to come by than they are in the UK.

You’re shit-out-of-luck if you’re thinking you’d prefer a European-style pay-as-you-go (PAYG) approach. The options are thin on the ground. Any airtime you buy means just that – any time you spend talking or texting – so you pay to send and receive calls or SMS’s. My experience suggests that some networks recycle phone numbers or sell on your details. I still receive random texts addressed to previous owners of my phone number, and get messages from marketing companies who have miraculously acquired my personal details, an irritation that is compounded by the fact that it costs you money to be harassed.

If you’re determined to go the PAYG route, the nearest US equivalent is probably AT&T’s GoPhone SIM or Net10. You’ll have to purchase a phone and credit up front; top ups can be purchased in store, at some supermarkets, or done over the phone. This may also be the first time you encounter the US concept of a “restocking fee” – a method of dissuading you from returning items by charging you to do so. The restocking fee for the burner phone I first purchased was almost as much as the phone itself.

Open a bank account, transfer money

Make this a top priority. You should open a bank account as soon as you arrive in the US, especially as some banks will initially let you do so without a Social Security Number or permanent address.

Until you open a US bank account, you’ll be haemorrhaging money on fees levied by your UK bank for dollar transactions, and subject to poor exchange rates.

Choose a bank

San Francisco has a large range of different bank brands to choose from, but you’re probably best sticking to the big name banks that have branches and ATMs throughout the city, such as Bank of America, Chase, or Wells Fargo. There are co-ops and niche services if that’s your thing. Be sure to do some preparatory research on which bank is best suited to your needs. It’s also worth checking if your bank in the UK has a reciprocal agreement with any bank operating in San Francisco; it may cut down the cost of moving your money. Friends recommended going with either Bank of America or Chase. I went with Bank of America, where the customer service was personal and friendly.

Banking fees are a matter of course in the US. In contrast to the UK, you’ll almost certainly be charged for withdrawing money from any ATMs that aren’t owned by your bank. You have to buy cheque books (“check” in American English) and pay a fee to transfer your money to accounts outside your bank. Accounts usually involve a monthly fee, although this is waived in certain situations, such as setting up your salary to be directly deposited. Expect to set up a current (“checking”) and savings account, and to be asked to make a minimum cash deposit to complete the process (at Bank of America it was $100).

Once you’re all set up, your debit card will be sent in the post – so make sure you’ll be at that address for at least another week. In the meantime you may get a temporary cash card to get at what you’ve already deposited. Even if you transfer more money in, your bank can limit the amount you can withdraw within the first 30 days of the account being open – presumably to combat fraud/laundering.

Transfer money

It’s essential that you transfer money from your UK bank as soon as possible. There are many factors to consider when calculating how much money you want to transfer.

• You may enter the US up to 10 days before your visa is valid and you can start work.
• You need money for food, transport, going out, a phone (and deposit), apartment applications, an apartment deposit, buying furniture, etc.
• You might not be able to get paid until you have a Social Security Number.
• You’re unlikely to get paid until the middle or end of the month you start working.
• You’re very likely to get your first pay cheque given to you as a real cheque; your bank is then likely to withhold the vast majority of the cheque’s value for up to 28 days.
• It will cost you several thousand dollars – a deposit and at least one month of rent – to secure an apartment. In general, landlords will not accept a UK banking cheque.
• You’ll have to buy furniture and general household items if you aren’t shipping any from the UK.

All in all, this means you may end up without any significant US-earned money in your account for 30-45 days while making some of the biggest expenses you’re likely to have made for a while.

Transferring money to a US bank account can be done online via wire transfer between banks. Unfortunately, my bank in the UK – Santander – didn’t allow online wire transfers so I had to look for alternatives. You may want to research this prior to leaving the UK!

The Post Office provide a simple, secure, and fee-free service, but a poorer exchange rate. Looking around, I came across Currencyfair – a peer-to-peer currency exchange service. They provide online quotes without the need to sign up, they were very prompt and helpful in their replies to questions I had, and the exchange rate was very good. Overall, I saved quite a bit of money and I’d rely on them in the future.

Get a Clipper card

The Clipper card is San Francisco’s equivalent of London’s Oyster card. Getting one will take some of the pain out of using the various modes of public transport in San Francisco. You can get a Clipper card online and I’d suggest setting up “Autoload” (you’ll need a bank account) to get the card for free and never worry about remembering to top up your credit. Alternatively, you can buy them on the high street from shops like Walgreens.

Get a Social Security Number

Social Security recommend that you only apply for a Social Security Number once you’ve been in the US over 10 days.

My experience was that the process is quick and simple. You complete a short SSN application form ahead of time and take it to the nearest Social Security office along with the documentation they advise you to bring. Arrive first thing in the morning to avoid any wait. It can take a few weeks for your Social Security card to arrive so you may want to have it sent to your employer’s address if you don’t have a permanent address yet.

Once you have your Social Security Card, you should keep it safe and be judicious in giving your SSN out. However, you should provide it to your bank and employer as soon as possible.

Find somewhere to live

Living in the city of San Francisco is just one of the (more expensive) options available to you. I chose to live in the city but many of my friends and colleagues live in other areas, like the East Bay. Have a look around before making up your mind.

Rent is very expensive in San Francisco, even compared to prices in London, especially since it’s very rare to find furnished accommodation. It also appears to be rising at a staggering rate. However, buildings constructed before June 1979 are covered by San Francisco Rent Control which heavily constrains the rate at which your rent can increase once you become a tenant. Therefore, it’s worth taking the time to find somewhere that you could imagine living for a few years.

The rental market is extremely competitive. Many places rely on one-off, brief, herd-style viewings where you’re in the apartment with half a dozen other desperate people at the same time, and more arriving every minute. People hand over all their paperwork and a cash application fee (if applicable) there and then.

Things are made slightly harder because you’re unlikely to have any US credit history, which is something quite important over here. But an offer letter and salary details from a tech company seems to put you in good shape. It’s in your best interest to put together a dossier of papers to provide alongside any application you make. You should include scans of your employer’s offer letter, your visa, and ideally character references from a previous landlord, etc. Print out several copies to take with you to viewings. You might have to pay $30-$40 to make an application (which is meant to cover credit history checks), but I never did.

I found that using Craigslist or a listing aggregator like Lovely was the best way to find apartments for rent in the city. They will also help you to narrow your focus to the neighbourhoods that you’re most interested in (spend some time learning about the city). Before moving to San Francisco, I heard a lot of stories about how it was essential – if you are to have any hope – to be “first” to make contact with the poster of a listing, but my experience was that you’re generally given the date and time of a mass-viewing to attend. This means that making a good impression in person, and having a bit of a chat with your potential landlord or building-manager, is likely to improve your chances and help you make a decision. Be prepared for it to take a while to find an apartment – it took me over a month of searching.

Once you’ve found a place to rent and signed all the paperwork, call PG&E to create an account to pay for your heat and electricity. You can set up e-bills and automatic payments online once your account has been processed. It’s a good idea to sort out an ISP before you move in – I went with Sonic.net. Again, the monthly cost (which I was told includes 17 different taxes and “renting” of the router) is a little higher than you’d expect in the UK, and you can expect to pay an installation fee. Other things to do: get Renters Insurance and have your bank automatically mail out your monthly-rent check to your landlord or building manager. All these things are quick and easy to do.

If you’re interested in your renters rights, you can search the California Department of Consumer Affairs for information.

Buying stuff for your place

You’re going to need furniture and basic household items. There’s always Ikea, which is located in Emeryville across the bay. If you have any previous Ikea experience, you’ll know that it’s one of the most stressful shopping experiences imaginable. The Ikea in Emeryville is even worse but the prices are pretty good. You can get there by bus from San Francisco and have large items delivered, or sort out your own transport.

Other stores to look at include West Elm and Crate & Barrel; they sell nicer things but are significantly more expensive. Alternatively, there are a lot of independent and second-hand furniture shops in San Francisco, particularly in the Mission district and a few along Van Ness. They’re well worth checking out. Van Ness also has 3 or 4 stores that sell mattresses – Sleep Train came particularly well recommended. I’d suggest that you leverage the lower costs of similar mattresses online in order to significantly reduce the price of your purchase, while benefiting from the great service, free delivery, and returns policy of the high-street stores. And if you have no idea what you’re doing: home decor tips, infographics, and cheat sheets

Get a California I.D.

Once you have your SSN and have found a permanent address, you should apply for a California I.D. at the DMV. This is handy if you don’t want to carry your passport (with visa) around and don’t have alternative I.D., such as a driver’s licence. You should register for an appointment to avoid a long wait in line. It can take up to 60 days for your California I.D. to arrive.

Get a credit card

The U.S. revolves around consumer credit. You need to start building up a credit history as soon as possible if you want to avoid paying large deposits or higher prices. Ask your bank about the soonest that you can apply for a credit card and then start using it – buying on credit even if you don’t need to.

Inform HMRC and the Student Loans Company

Once you’re settled, you should make time to inform HMRC that you’ve left the UK. They’ll be able to assess your tax status. If you are repaying student loans, after 3 months in the US you’re expected to contact the Student Loans Company by completing an overseas income assessment form. They will then work out your repayments.

Welcome to the United States of America

Hopefully you settle in within a couple of months and get to know San Francisco. There are many faces to this city, but the social scene is pretty diverse and there are many restaurants, bars, cafes, parks, and attractions – plenty of places to explore and things to do while you find your feet.

For the first time since coming back to San Francisco in January, I had everything I needed for a saunter across the city in the sun: a means of taking photos / videos, a pair of sunglasses, no work, no plans, and no excuse.

On the morning of July 4th, I decided to spend the next couple of days offline. I read a book, and decided to go for a walk the rest of the day. I didn’t have any expectations or intended destination. I left my apartment at 2pm and decided to walk west, as I haven’t spent any proper time on that side of the city.

I passed through a couple of small parks and quiet neighbourhoods before hitting the edge of The Presidio.

At this point, I realised how long it had been since I’d seen a large expanse of something approximating nature. The Presidio was beautifully tranquil, with just a handful of people strolling or running through the trees. Walking off the trails, I saw a lizard for the first time in years; probably a San Francisco Alligator Lizard.

I exited The Presidio somewhere near the golf course and picked a long road to keep walking west.

On the way, I hit a main road and stood at the traffic lights. While I waited a young woman walking her dog struck up the first of several impromptu conversations I had with strangers that day. She must have seen me looking around for the street name, as she asked, “Are you lost? Are you a tourist? Where are you going?”

“I’m not sure. That way”, I said pointing down the long road before us.

She laughed. “See, you are lost!”

We chatted for a few blocks before our paths diverged. She told me that I would find some nice trails, and a good view of the Golden Gate Bridge, in the woodland near Lands End. It was dead ahead for another 30 minutes. So that’s where I went.

I hit the trails at about 4:30pm. It must have been close to perfect weather. Really sunny, warm, only a mild breeze, and the bay was completely clear. I wandered around for over an hour; perching near the edge of cliffs, taking in the sight of the Golden Gate Bridge on my right and a vast expanse of ocean to my left. Such a relaxing place.

I made time for a Dorsey-like Vine (my first Vine)…

On the way back, I crossed a road to take a photo. A post-middle-age man crossed my path, struck up a conversation, and began to tell me about his life in San Francisco “back in the day”. As if he could peer into my soul, he assured me that there was nothing wrong with being a software engineer (although he did initially think I was an estate agent; that was one of the first things he said to me).

My spirits further lifted by a stranger’s validation, I continued home. For last 30 minutes all I could think about was lying down, resting my feet, and eating. I’d been walking for nearly 6 hours. I’ll definitely do it again, but a skateboard would be helpful next time.

I recently included the option to add a large cover image, like the one above, to my posts. The source image is cropped, and below specific maximum dimensions it’s displayed at a predetermined aspect ratio. This post describes the implementation.

• Demo: Flexible CSS cover images

Known support: Chrome, Firefox, Safari, Opera, IE 9+

Features

The way that the cover image scales, and changes aspect ratio, is illustrated in the following diagram.

The cover image component must:

• render at a fixed aspect ratio, unless specific maximum dimensions are exceeded;
• support different aspect ratios;
• support max-height and max-width;
• support different background images;
• display the image to either fill, or be contained within the component;
• center the image.

Aspect ratio

The aspect ratio of an empty, block-level element can be controlled by setting a percentage value for its padding-bottom or padding-top. Given a declaration of padding-bottom:50% (and no explicit height), the rendered height of the element will be 50% of its width.

.CoverImage {
  padding-bottom: 50%;
}

Changing that padding value will change the aspect ratio. For example, padding of 25% results in an aspect ratio of 4:1, padding of 33.333% results in an aspect ratio of 3:1, etc.

Maximum dimensions

The problem with using this aspect ratio hack is that if the element has a max-height declared, it will not be respected. To get around this, the hack can be applied to a pseudo-element instead.

.CoverImage:before {
  content: "";
  display: block;
  padding-bottom: 50%;
}

Now the main element can take a max-height. It should also clip the pseudo-element overflow.

.CoverImage {
  display: block;
  max-height: 300px;
  max-width: 1000px;
  overflow: hidden;
}

.CoverImage:before {
  content: "";
  display: block;
  padding-bottom: 50%;
}

This aspect ratio pattern is provided by the FlexEmbed component for SUITCSS. That component is primarily for responsive video embeds, but it’s flexible enough to be useful whenever you need an element rendered at a predetermined aspect ratio. It comes with modifiers for 2:1, 3:1, 16:9, and 4:3 aspect ratios. The cover image component can extend the FlexEmbed component.

<div class="CoverImage FlexEmbed FlexEmbed--2by1"></div>

Background image

The cover image is applied as a background image that is sized to cover the entire area of the element. This makes sure the image is clipped to fit the aspect ratio of the element.

.CoverImage {
  ...
  background-repeat: no-repeat;
  background-size: cover;
}

If you want different cover images for different instances of the component, they can be applied via the style attribute.

<div class="..." style="background-image: url(cover.jpg)"></div>

The image can be fully centered by using background positioning and block centering. This makes sure that the image is centered in the element, and that the element is centered within its parent (when it reaches the max-width value).

.CoverImage {
  ...
  background-position: 50%;
  background-repeat: no-repeat;
  background-size: cover;
  margin: 0 auto;
}

Final result

If you depend on the FlexEmbed module, the amount of additional code required is minimal. (See the demo for all the code, including the FlexEmbed dependency.)

/**
 * Requires: suitcss/flex-embed
 */

.CoverImage {
  background-position: 50%;
  background-repeat: no-repeat;
  background-size: cover;
  margin: 0 auto;
  max-height: 300px;
  max-width: 1000px;
}

<div class="CoverImage FlexEmbed FlexEmbed--3by1"
     style="background-image:url(cover.jpg)">
</div>

You can add further customizations, such as setting the accompanying background color, or providing a means to switch between the cover and contain keywords for background-size.

I’m working on a project at Twitter that uses React and webpack. After a few conversations with @sokra last year, this is the setup I put in place for testing React components (authored using JSX and ES6) using Karma.

Dependencies

You’ll need to install various packages. It looks like a lot of dependencies, but all the non-Karma packages will be necessary for general module bundling during development.

Full set of required packages:

• babel-core: to transform JSX and transpile ES6.
• babel-loader: webpack loader for Babel.
• karma: the test runner.
• karma-chai-plugins: assertion library (or your library of choice).
• karma-chrome-launcher: Chrome browser launcher.
• karma-cli: CLI tool for Karma.
• karma-mocha: adapter for the Mocha testing framework.
• karma-sourcemap-loader: sourcemap loader.
• karma-webpack: to use webpack with Karma.
• react
• webpack: module bundler

webpack entry file

If you use webpack-specific features in your modules (e.g., loaders, plugins) you will need to use webpack to build a test bundle. The fastest and simplest approach is to create a single, test-specific entry file.

Create a file named tests.bundle.js. Within this file, you create a webpack context to match all the files that conform to a naming pattern – in this case *.spec.js(x).

var context = require.context('.', true, /.+.spec.jsx?$/);
context.keys().forEach(context);
module.exports = context;

Next, you point Karma to this file.

Karma config

Karma is configured using a karma.conf.js file. The browsers, plugins, and frameworks are specified in the standard way.

Point Karma at the tests.bundle.js file, and run it through the relevant preprocessor plugins (see example below).

The karma-webpack plugin relies on 2 custom properties of the Karma config: webpack and webpackMiddleware. The value of the former must be a webpack config object.

module.exports = function (config) {
  config.set({
    browsers: [ 'Chrome' ],
    // karma only needs to know about the test bundle
    files: [
      'tests.bundle.js'
    ],
    frameworks: [ 'chai', 'mocha' ],
    plugins: [
      'karma-chrome-launcher',
      'karma-chai',
      'karma-mocha',
      'karma-sourcemap-loader',
      'karma-webpack',
    ],
    // run the bundle through the webpack and sourcemap plugins
    preprocessors: {
      'tests.bundle.js': [ 'webpack', 'sourcemap' ]
    },
    reporters: [ 'dots' ],
    singleRun: true,
    // webpack config object
    webpack: {
      devtool: 'inline-source-map',
      module: {
        loaders: [
          {
            exclude: /node_modules/,
            loader: 'babel-loader,
            test: /.jsx?$/
          }
        ],
      }
    },
    webpackMiddleware: {
      noInfo: true,
    }
  });
};

Rather than duplicating your webpack config, you can require it in the Karma config file and override the devtool value to get sourcemaps working.

var webpackConfig = require('./webpack.config');
webpackConfig.devtool = 'inline-source-map';

module.exports = function (config) {
  config.set({
    ...
    webpack: webpackConfig
  });
};

That’s all you need to do to configure Karma to use webpack to load your JSX, ES6 React components.

Twitter Lite uses Redux for state management and relies on code-splitting. However, Redux’s default API is not designed for applications that are incrementally-loaded during a user session.

This post describes how I added support for incrementally loading the Redux modules in Twitter Lite. It’s relatively straight-forward and proven in production over several years.

Redux modules

Redux modules comprise of a reducer, actions, action creators, and selectors. Organizing redux code into self-contained modules makes it possible to create APIs that don’t involve directly referencing the internal state of a reducer – this makes refactoring and testing a lot easier. (More about the concept of redux modules.)

Here’s an example of a small “redux module”.

// data/notifications/index.js

const initialState = [];
let notificationId = 0;

const createActionName = name => `app/notifications/${name}`;

// reducer
export default function reducer(state = initialState, action = {}) {
  switch (action.type) {
    case ADD_NOTIFICATION:
      return [...state, { ...action.payload, id: notificationId += 1 }];
    case REMOVE_NOTIFICATION:
      return state.slice(1);
    default:
      return state;
  }
}

// selectors
export const selectAllNotifications = state => state.notifications;
export const selectNextNotification = state => state.notifications[0];

// actions
export const ADD_NOTIFICATION = createActionName(ADD_NOTIFICATION);
export const REMOVE_NOTIFICATION = createActionName(REMOVE_NOTIFICATION);

// action creators
export const addNotification = payload => ({ payload, type: ADD_NOTIFICATION });
export const removeNotification = () => ({ type: REMOVE_NOTIFICATION });

This module can be used to add and select notifications. Here’s an example of how it can be used to provide props to a React component.

// components/NotificationView/connect.js

import { connect } from 'react-redux';
import { createStructuredSelector } from 'reselect';
import { removeNotification, selectNextNotification } from '../../data/notifications';

const mapStateToProps = createStructuredSelector({
  nextNotification: selectNextNotification
});
const mapDispatchToProps = { removeNotification };

export default connect(mapStateToProps, mapDispatchToProps);

// components/NotificationView/index.js

import connect from './connect';
export class NotificationView extends React.Component { /*...*/ }
export default connect(NotificationView);

This allows you to import specific modules that are responsible for modifying and querying specific parts of the overall state. This can be very useful when relying on code-splitting.

However, problems with this approach are evident once it comes to adding the reducer to a Redux store.

// data/createStore.js

import { combineReducers, createStore } from 'redux';
Import notifications from './notifications';

const initialState = /* from local storage or server */

const reducer = combineReducers({ notifications });
const store = createStore(reducer, initialState);

export default store;

You’ll notice that the notifications namespace is defined at the time the store is created, and not by the Redux module that defines the reducer. If the “notifications” reducer name is changed in createStore, all the selectors in the “notifications” Redux module no longer work. Worse, every Redux module needs to be imported in the createStore file before it can be added to the store’s reducer. This doesn’t scale and isn’t good for large apps that rely on code-splitting to incrementally load modules. A large app could have dozens of Redux modules, many of which are only used by a few components and unnecessary for initial render.

Both of these issues can be avoided by introducing a Redux reducer registry.

Redux reducer registry

The reducer registry enables Redux reducers to be added to the store’s reducer after the store has been created. This allows Redux modules to be loaded on-demand, without requiring all Redux modules to be bundled in the main chunk for the store to correctly initialize.

// data/reducerRegistry.js

export class ReducerRegistry {
  constructor() {
    this._emitChange = null;
    this._reducers = {};
  }

  getReducers() {
    return { ...this._reducers };
  }

  register(name, reducer) {
    this._reducers = { ...this._reducers, [name]: reducer };
    if (this._emitChange) {
      this._emitChange(this.getReducers());
    }
  }

  setChangeListener(listener) {
    this._emitChange = listener;
  }
}

const reducerRegistry = new ReducerRegistry();
export default reducerRegistry;

Each Redux module can now register itself and define its own reducer name.

// data/notifications/index.js

import reducerRegistry from '../reducerRegistry';

const initialState = [];
let notificationId = 0;

const reducerName = 'notifications';

const createActionName = name => `app/${reducerName}/${name}`;

// reducer
export default function reducer(state = initialState, action = {}) {
  switch (action.type) {
    case ADD_NOTIFICATION:
      return [...state, { ...action.payload, id: notificationId += 1 }];
    case REMOVE_NOTIFICATION:
      return state.slice(1);
    default:
      return state;
  }
}

reducerRegistry.register(reducerName, reducer);

// selectors
export const selectAllNotifications = state => state[reducerName];
export const selectNextNotification = state => state[reducerName][0];

// actions
export const ADD_NOTIFICATION = createActionName(ADD_NOTIFICATION);
export const REMOVE_NOTIFICATION = createActionName(REMOVE_NOTIFICATION);

// action creators
export const addNotification = payload => ({ payload, type: ADD_NOTIFICATION });
export const removeNotification = () => ({ type: REMOVE_NOTIFICATION });

Next, we need to replace the store’s combined reducer whenever a new reducer is registered (e.g., after loading an on-demand chunk). This is complicated slightly by the need to preserve initial state that may have been created by reducers that aren’t yet loaded on the client. By default, once an action is dispatched, Redux will throw away state that is not tied to a known reducer. To avoid that, reducer stubs are created to preserve the state.

// data/createStore.js

import { combineReducers, createStore } from 'redux';
import reducerRegistry from './reducerRegistry';

const initialState = /* from local storage or server */

// Preserve initial state for not-yet-loaded reducers
const combine = (reducers) => {
  const reducerNames = Object.keys(reducers);
  Object.keys(initialState).forEach(item => {
    if (reducerNames.indexOf(item) === -1) {
      reducers[item] = (state = null) => state;
    }
  });
  return combineReducers(reducers);
};

const reducer = combine(reducerRegistry.getReducers());
const store = createStore(reducer, initialState);

// Replace the store's reducer whenever a new reducer is registered.
reducerRegistry.setChangeListener(reducers => {
  store.replaceReducer(combine(reducers));
});

export default store;

Managing the Redux store’s reducer with a registry should help you better code-split your application and modularize your state management.

Using SVG is currently the best way to create icon libraries for apps. Icons built with SVG are scalable and adjustable, but also discrete, which allows them to be incrementally loaded and updated. In contrast, icons built as fonts cannot be incrementally loaded or updated. This alone makes SVG icons the better choice for high-performance apps that rely on code-splitting and incremental deploys.

This post describes how to make a package of React components from a library of SVG icons. Although I’m focusing on React, making any other type of package is also possible. At Twitter I used the approach described here to publish the company’s SVG icon library in several different formats: optimized SVGs, plain JavaScript modules, React DOM components, and React Native components.

Using the icons

The end result is a JavaScript package that can be installed and used like any other JavaScript package.

yarnpkg add @acme/react-icons

Each icon is available as an individually exported React component.

import IconCamera from '@acme/react-icons/camera';

This allows your module bundler to package only the icons that are needed, and icons can be efficiently split across chunks when using code-splitting. This is a significant advantage over icon libraries that require fonts and bundle all icons into a single component.

// entire icon library is bundled with your app
import Icon from '@acme/react-icons';
const IconCamera = <Icon name='camera' />;

Each icon is straightforward to customize (e.g., color and dimensions) on a per-use basis.

import IconCamera from '@twitter/react-icons/camera';
const Icon = (
  <IconCamera
    style={{ color: 'white', height: '2em' }}
  />
);

Although the icons render to SVG, this is an implementation detail that isn’t exposed to users of the components.

Creating components

Each React component renders an inline SVG, using path and dimensions data extracted from the SVG source files. A helper function called createIconComponent means that only a few lines of boilerplate are needed to create a component from SVG data.

import createIconComponent from './utils/createIconComponent';
import React from 'react';
const IconCamera = createIconComponent({
  content: <g><path d='...'></g>,
  height: 24,
  width: 24
});
IconCamera.displayName = 'IconCamera';
export default IconCamera;

This is an example of what the createIconComponent function looks like when building components for a web app like Twitter Lite, which is built with React Native for Web.

// createIconComponent.js
import { createElement, StyleSheet } from 'react-native-web';
import React from 'react';

const createIconComponent = ({ content, height, width }) =>
  (initialProps) => {
    const props = {
      ...initialProps,
      style: StyleSheet.compose(styles.root, initialProps.style),
      viewBox: `0 0 ${width} ${height}`
    };

    return createElement('svg', props, content);
  };

const styles = StyleSheet.create({
  root: {
    display: 'inline-block',
    fill: 'currentcolor',
    height: '1.25em',
    maxWidth: '100%',
    position: 'relative',
    userSelect: 'none',
    textAlignVertical: 'text-bottom'
  }
});

Setting the fill style to currentcolor allows you to control the color of the SVG using the color style property instead.

All that’s left is to use scripts to process the SVGs and generate each React component.

Creating icon packages

A complete example of one way to do this can be found in the icon-builder-example repository on GitHub.

The project structure of the example tool looks like this.

.
├── README.md
├── package.json
├── scripts/
    ├── build.js
    ├── createReactPackage.js
    └── svgOptimize.js
└── src/
    ├── alerts.svg
    ├── camera.svg
    ├── circle.svg
    └── ...

The build script uses SVGO to optimize the SVGs, extract SVG path data, and extract metadata. The example packager for React then uses templates to create a package.json and the React icon components shown earlier.

import createIconComponent from './utils/createIconComponent';
import React from 'react';
const ${componentName} = createIconComponent({
  height: ${height},
  width: ${width},
  content: <g>${paths}</g>
});
${componentName}.displayName = '${componentName}';
export default ${componentName};

Additional packagers can be included to build other package types from the same SVG source. When the underlying icon library changes, it only takes a couple of commands to rebuild hundreds of icons and publish new versions of each package.

The Home Ministry had on Thursday allowed chariot construction with a condition that no religious congregation should take place around the Ratha Khala.

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Two prominent medical experts — AIIMS director Dr Randeep Guleriya and Dr. Manish Suneja — flew into Ahmedabad on Friday following instructions from the Home Minister to guide local doctors

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Material brought illegally in vehicles that had permission to carry fruits and vegetables

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The NCMC chaired by Cabinet Secretary Rajiv Gauba met on Friday to review the situation arising out of the gas leak

All returnees are taken to centres from buses and trains

Rupa Rani Bhuyan, assistant professor of Mangaldoi College, was held for “misbehaving” with the police and “obstructing” them from investigating cases against her

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State health officials are planning extensive tests