Conditional comments work as follows:

复制代码 代码如下:

<>

[code]

Their basic structure is the same as an HTML comment (<>). Therefore all other browsers will see them as normal comments and will ignore them entirely.

IE, though, has been programmed to recognize the special <[if IE]>

According to the conditional comment this is IE<br />

<![endif]-->

<>

<>

<>

<>

<>

<>

<>

<>

<>

According to the conditional comment this is not IE<br />

<>

</p>

Note the special syntax:

gt: greater than

lte: less than or equal to

Also note the last one. It has a different syntax, and its contents are shown in all browsers that are not IE:

复制代码 代码如下:

<>

CSS hack?

Are conditional comments CSS hacks? Strictly speaking, yes, since they can serve to give special style instructions to some browsers. However, they do not rely on one browser bug to solve another one, as all true CSS hacks do. Besides, they can be used for more than CSS hacks only (though that rarely happens).

Since conditional comments are not based on a browser hack but on a deliberate feature I believe they are safe to use. Sure, other browsers could implement conditional comments, too (though as yet none have done so), but they're unlikely to react to the specific query <!--[if IE]>.

I use conditional comments, though sparingly. First I see if I can find a real CSS solution to an Explorer Windows problem. If I can't, though, I don't hesitate to use them.

Comment tag

A reader told me IE also supports the (non-standard) <comment> tag.

<p>This is <comment>not</comment> IE.</p>

This isIE.

This tag might be a replacement for the !IE conditional comment.