What is IE=Edge in GCF used for? [duplicate]

Question

The Google chrome frame developer guide says,

The following complete example indicates usage of Google Chrome Frame for IE6 users, and otherwise passes the "Edge" parameter to later versions of IE:

<meta http-equiv="X-UA-Compatible" content="IE=Edge,chrome=IE6">

What does "passing the EDGE parameter to later versions of IE" means?

Pupiparous

Answer 1

From MSDN Defining Document Compatibility

Document compatibility modes allow you to control the way Internet Explorer interprets and displays your webpage

Specifying IE=edge instructs IE to use highest available engine for established and emerging industry standards.

For example in IE9 the highest version of the engine is 9 (likewise the highest version for IE8 is 8), but IE9 can also render a web page using the IE8, IE7 or IE5 engine (with all of their old bugs) and IE8 can also render pages as IE7 or IE5 did.

If you have a page that was designed for IE7 but a user is now using IE9 has the page breaks; rather than updating all the code to work with both engines one can add the <meta> tag speficying that IE9 use the IE7 engine.

The Chrome frame recommendation is recommending this to future proof the code against new releases of IE. By specifying "use the latest version" you are not limiting the page to a specific version of IE.

In the context of your question I don't think that using Edge is specific to the GCF, but rather an instruction to IE.

Aspirant

ChromeFrame is dead now, of course. – Empire

Answer 2

It makes IE use the most up to date version of the rendering engine.

http://msdn.microsoft.com/en-us/library/cc288325(v=vs.85).aspx

Godden

For example, If we take IE8 browser, what is the most up-to-date version of the rendering engine available? – Pupiparous

It is whatever browser version you have, so IE8 in that case. – Godden

Answer 3

http://msdn.microsoft.com/en-us/library/jj676915(v=vs.85).aspx

Note Edge mode is intended for testing purposes only; do not use it in a production environment.

Curiosity