When serving JavaScript files, is it better to use the application/javascript or application/x-javascript

The whole question fits in the title. And to add some context: I’m not asking what is the best according to what the specs are saying, but rather what works the best given the mix of browsers deployed nowadays.

Some data points:

• Google uses text/javascript for the JS used on their home page.
• Google uses text/javascript on Google Docs.
• Google uses application/x-javascript to serve JavaScript files with their Ajax libraries service.
• Yahoo uses application/x-javascript to serve their JS.
• Yahoo uses application/x-javascript for the JavaScript served on their home page.

Answer

According to the IETF’s ECMAScript Media Types Updates as of 22 February 2021, the RFC-4329 is obsolete.

Therefore:

• text/javascript is a recommended standard (both by IETF and by MDN)
• application/x-javascript was experimental while deciding to move to…
• application/javascript is obsolete