The type attribute specifies the media type of the script.
A media type, formerly known as a MIME type, indicates the format and nature of a script.
Browsers don't look at a resource's file extension, but rather what media type it is.
A list with common HTTP Media Types is available on this site.
Tip: The IANA organization maintains a list of all official media types.
Here is when type support started for each browser:
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