IE 8 and vendor prefixes
Tuesday, September 9th, 2008
I haven’t been posting much lately, since I’ve been focusing on actually getting things done, but I wanted to point out what I think is a very good decision from Microsoft that seems to show they’re really serious about standards.
Historically, CSS property vendor prefixes (-moz-, -o-, -khtml-, -ms-, …) have generally been used for properties that either aren’t part of a current CSS standard or are part of a current standard but only have experimental support by the browser. But most browsers have made exceptions to these rules depending on how common the non-prefixed versions are on the Web.
Microsoft has announced that they are taking a clear-cut approach to this topic and will always follow these convention rules. In Internet Explorer 8, webpages invoking the best standards mode (default) will be required to add an -ms- prefix to vendor-specific properties like filter, scrollbar-base-color, and zoom, as well as non-finalized CSS 3 features like background-position-x, overflow-x, and word-wrap.
Microsoft claims that every CSS 2.1 property will be considered supported, so no CSS 2.1 property will require a vendor prefix.
Now, here’s why I think this decision is so significant: Asking a browser to always follow the vendor prefix conventions is a picky request. An unreasonable request, some might say. I’ve argued about this subject a number of times in the past, and I’m usually dismissed as a silly idealist for wanting browsers to deliberately break support for current websites just to follow a convention with fairly hard-to-see benefits.
Most people don’t know or care that breaking the convention introduces possible complications for the development of future standards. They just want to see the “Passed Validation!” message in CSS 3 mode. They’re more concerned with the short term issues of getting all the lights to turn green than the long term issues of the growth and stability of sound web standards.
Microsoft’s decision makes some short-term sacrifices for the interest of the long term health of the Web, and it’s on an issue that even many standards advocates would consider picky. Well, I for one am thrilled to see Microsoft getting “picky” about the quality of their standards support.
Update 2008-09-09: I should clarify that the non-prefixed properties that were supported in IE 7 will continue to be supported in IE 8, with or without the prefix. But Microsoft considers the non-prefixed versions deprecated, and they may be removed in a future version.
The exception is the filter property, which will not work in IE 8 standards mode without the prefix. This is because the original filter syntax didn’t comply with CSS’s grammar rules and will thus be ignored in IE 8’s improved CSS parser. If you have to continue using the filter property, you need to include the prefix and put quotes around the property value. For compatibility with older versions of IE, you’ll need to write the filter both ways.