问题
<meta http-equiv="X-UA-Compatible" content="IE=9; IE=8; IE=7; IE=EDGE" />
Actually what is the meaning of this statement ?
Some of the examples use
,to separate versions of IE, while some use;; which is correct?The order
IE=9; IE=8; IE=7; IE=EDGEhas some importance, I wish to know that.
Edit: I am using <!DOCTYPE html>
回答1:
If you support IE, for versions of Internet Explorer 8 and above, this:
<meta http-equiv="X-UA-Compatible" content="IE=9; IE=8; IE=7" />
Forces the browser to render as that particular version's standards. It is not supported for IE7 and below.
If you separate with semi-colon, it sets compatibility levels for different versions. For example:
<meta http-equiv="X-UA-Compatible" content="IE=7; IE=9" />
Renders IE7 and IE8 as IE7, but IE9 as IE9. It allows for different levels of backwards compatibility. In real life, though, you should only chose one of the options:
<meta http-equiv="X-UA-Compatible" content="IE=8" />
This allows for much easier testing and maintenance. Although generally the more useful version of this is using Emulate:
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8" />
For this:
<meta http-equiv="X-UA-Compatible" content="IE=Edge" />
It forces the browser the render at whatever the most recent version's standards are.
For more information, there is plenty to read about on MSDN,
回答2:
In certain cases, it might be necessary to restrict the display of a webpage to a document mode supported by an earlier version of Internet Explorer. You can do this by serving the page with an x-ua-compatible header. For more info, see Specifying legacy document modes.
- https://msdn.microsoft.com/library/cc288325
Thus this tag is used to future proof the webpage, such that the older / compatible engine is used to render it the same way as intended by the creator.
Make sure that you have checked it to work properly with the IE version you specify.
来源：https://stackoverflow.com/questions/14611264/x-ua-compatible-content-ie-9-ie-8-ie-7-ie-edge