Best content type to serve JSONP?

Question

I have a webservice that when called without specifying a callback will return a JSON string using application/json as the content type.

When a callback is specified it will wrap the JSON string in a callback function, so it's not really valid JSON anymore. My question is, should I serve it as application/javascript in this case or still use application/json?

score 147 · Accepted Answer · edited May 02 '18 at 04:46

147

Use application/javascript. In that way, clients can rely on the content-type without having to manually check whether a response has padding or not.

edited May 02 '18 at 04:46

apaderno

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answered Sep 21 '08 at 16:06

John Millikin

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1

It fails in IE 9 with message "SEC7112: Script from http://xyz.com was blocked due to mime type mismatch " Any idea why ? – Pit Digger Sep 12 '11 at 20:05
Content type "application/javascript" may mismatch with "text/javascript" that specified in script tag (or expected by default for some reason) – Ievgen Lukash Mar 26 '13 at 21:18
Based on the information in [this article](http://blogs.msdn.com/b/ie/archive/2010/10/26/mime-handling-changes-in-internet-explorer.aspx) text/javascript and application/javascript would work in IE 9. I wonder @pit-digger if the server just wasn't returning the correct content-type header. – spig May 06 '14 at 14:13

score 122 · Answer 2 · edited Nov 12 '11 at 00:37

122

Use application/json as per rfc4627.txt if what you return is plain JSON.

If you return JavaScript (which is really what JSONP is), then use application/javascript as per rfc4329.txt

edited Nov 12 '11 at 00:37

Brad

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answered Sep 21 '08 at 16:10

Florian Bösch

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Best content type to serve JSONP?

2 Answers2

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