When to use the JavaScript MIME type application javascript instead of text javascript

Question

Based on the question jQuery code not working in IE  text javascript is used in HTML documents so Internet Explorer can understand it   But I   m wondering  when would you use application javascript  and more importantly  why would you use it instead of text javascript

User · Answer

application because  js-Files aren t something a user wants to read but something that should get executed

User · Answer

In theory  according to RFC 4329  application javascript   The reason it is supposed to be application is not anything to do with whether the type is readable or executable  It s because there are custom charset-determination mechanisms laid down by the language type itself  rather than just the generic charset parameter  A subtype of text should be capable of being transcoded by a proxy to another charset  changing the charset parameter  This is not true of JavaScript because   a  the RFC says user-agents should be doing BOM-sniffing on the script to determine type  I m not sure if any browsers actually do this though    b  browsers use other information   the including page s encoding and in some browsers the script charset attribute   to determine the charset  So any proxy that tried to transcode the resource would break its users   Of course in reality no-one ever uses transcoding proxies anyway  but that was the intent    Therefore the exact bytes of the file must be preserved exactly  which makes it a binary application type and not technically character-based text   For the same reason  application xml is officially preferred over text xml  XML has its own in-band charset signalling mechanisms  And everyone ignores application for XML  too   text javascript and text xml may not be the official Right Thing  but there are what everyone uses today for compatibility reasons  and the reasons why they re not the right thing are practically speaking completely unimportant

User · Answer

The problem with Javascript s MIME type is that there hasn t been a standard for years  Now we ve got application javascript as an official MIME type   But actually  the MIME type doesn t matter at all  as the browser can determine the type itself  That s why the HTML5 specs state that the type  text javascript  is no longer required

User · Answer

application javascript is the correct type to use but since it s not supported by IE6-8 you re going to be stuck with text javascript  If you don t care about validity  HTML5 excluded  then just don t specify a type

[javascript] When to use the JavaScript MIME type application/javascript instead of text/javascript?

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