Difference between application x-javascript and text javascript content types

Question

What is the difference between these headers   Content-Type  application javascript Content-Type  application x-javascript Content-Type  text javascript   Which one is best and why   Please do not say they are identical - if they were identical there would not have been three of them  I know both work - but I would like to know the difference

User · Answer

mime-types starting with x- are not standardized  In case of javascript it s kind of outdated   Additional the second code snippet   lt  Header  Content-Type  text javascript     gt    requires short open tags to be enabled  you should avoid it    lt  php Header  Content-Type  text javascript     gt    However  the completely correct mime-type for javascript is  application javascript   http   www iana org assignments media-types application index html

User · Answer

Use type  application javascript   In case of HTML5  the type attribute is obsolete  you may remove it  Note  that it defaults to  text javascript  according to w3 org  so I would suggest to add the  application javascript  instead of removing it      http   www w3 org TR html5 scripting-1 html attr-script-type   The type   attribute gives the language of the script or format of the data  If   the attribute is present  its value must be a valid MIME type  The   charset parameter must not be specified  The default  which is used if   the attribute is absent  is  text javascript     Use  application javascript   because  text javascript  is obsolete       RFC 4329  http   www rfc-editor org rfc rfc4329 txt         Deployed Scripting Media Types and Compatibility      Various unregistered media types have been used in an ad-hoc   fashion    to label and exchange programs written in ECMAScript and   JavaScript     These include        -----------------------------------------------------        text javascript            text ecmascript                  text javascript1 0         text javascript1 1               text javascript1 2         text javascript1 3               text javascript1 4         text javascript1 5               text jscript               text livescript                  text x-javascript          text x-ecmascript                application x-javascript   application x-ecmascript         application javascript     application ecmascript          -----------------------------------------------------            Use of the  text  top-level type for this kind of content is known to    be   problematic   This document thus defines text javascript and text    ecmascript but marks them as  obsolete    Use of experimental and   unregistered media types  as listed in part above  is discouraged    The media types       application javascript     application ecmascript       which are also defined in this document  are intended for common   use    and should be used instead       This document defines equivalent processing requirements for the   types text javascript  text ecmascript  and application javascript    Use of and support for the media type application ecmascript is   considerably less widespread than for other media types defined in   this document   Using that to its advantage  this document defines   stricter processing rules for this type to foster more interoperable   processing    x-javascript is experimental  don t use it

User · Answer

text javascript is obsolete  and application x-javascript was experimental  hence the x- prefix  for a transitional period until application javascript could be standardised    You should use application javascript  This is documented in the RFC   As far a browsers are concerned  there is no difference  at least in HTTP headers   This was just a change so that the text   and application   MIME type groups had a consistent meaning where possible   text   MIME types are intended for human readable content  JavaScript is not designed to directly convey meaning to humans    Note that using application javascript in the type attribute of a script element will cause the script to be ignored  as being in an unknown language  in some older browsers  Either continue to use text javascript there or omit the attribute entirely  which is permitted in HTML 5    This isn t a problem in HTTP headers as browsers universally  as far as I m aware  either ignore the HTTP content-type of scripts entirely  or are modern enough to recognise application javascript

User · Answer

According to RFC 4329 the correct MIME type for JavaScript should be application javascript  Howerver  older IE versions choke on this since they expect text javascript

[javascript] Difference between application/x-javascript and text/javascript content types

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