Supporting New Elements in IE
Internet Explorer poses a small challenge when it comes to making use of the new elements introduced in HTML5. Among others, these include elements like section, article, header and footer. The problem is that due to the way parsing works in IE, these elements are not recognised properly and result in an anomalous DOM representation.
To illustrate, consider this simple document fragment:
<body>
<section>
<p>This is an example</p>
</section>
</body>
Strangely, IE 6, 7 and 8 all fail to parse the section element properly and the resulting DOM looks like this.
BODYSECTIONP#text: This is an example
/SECTION
Notice how IE actually creates 2 empty elements. One named SECTION and the other named /SECTION. Yes, it really is parsing the end tag as a start tag for an unknown empty element.
There is a handy workaround available to address this problem, which was first revealed in a comment by Sjoerd Visscher.
The basic concept is that by using document.createElement(tagName) to create each of the unknown elements, the parser in IE then recognises those elements and parses them in a more reasonable and useful way. e.g. By using the following script:
document.createElement("section");
The resulting DOM for the fragment given above looks like this:
BODYsectionP#text: This is an example
This same technique works for all unknown elements in IE 6, 7 and 8. Note that there is a known bug that prevented this from working in IE 8 beta 2, but this has since been resolved in the latest non-public technical preview.
For convenience, Remy Sharp has written and published a simple script that provides this enhancement for all new elements in the current draft of HTML5, which you can download and use.
This script is not needed for other browsers. Opera 9, Firefox 3 and Safari 3 all parse unknown elements in a more reasonable way by default. Note, however, that Firefox 2 does suffer from some related problems, for which there is unfortunately no known solution; but it is hoped that given the faster upgrade cycle for users of Firefox, relatively speaking compared with IE, Firefox 2 won't pose too much of a problem in the future.