Manual:$wgJsMimeType

Output: $wgJsMimeType
Media type (MIME type) to use for JavaScript scripts.
Introduced in version:1.5.0 (r8895)
Deprecated in version:1.22.0 (Gerrit change 64638; git #1f956360)
Removed in version:1.34.0 (Gerrit change 522570; git #a8d26127)
Allowed values:(string)
Default value:'text/javascript'

Details edit

Use this variable to set the media type (MIME type) which is used for scripts written in the JavaScript scripting language.

See RFC 4329 and MediaWiki bug #2064 for details.

In theory, this should be set to 'application/javascript' for all new wikis. Standard-compliant browsers support this setting. Internet Explorer from Microsoft does not support it in its current version (version 7).