Regular expression to check for content type application/json etc

Question

This particular application is returning content-type headers in the format application/json;charset=UTF-8

I'm not sure if this could change and get reduced to 'application/json' only or may be if I reuse this code somewhere else for?

My code is

response.headers['Content-Type'].match(/text\/application//json/i)

How to best check for content type application/json???

score 3 · Accepted Answer · answered Jun 25 '16 at 22:59

3

You can use RegExp /application\/json/

var response = {"Content-Type":"application/json;charset=UTF-8"};
console.log(response["Content-Type"].match(/application\/json/)[0]);

answered Jun 25 '16 at 22:59

guest271314

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I am not sure that the [0] part is required. If no match, it will return null so parsing the first item of the array should throw an error. – Mark Odey Jul 05 '22 at 15:16
1

This will not work for `application/geo+json` – spacether Sep 05 '22 at 19:04

score 1 · Answer 2 · answered Jun 25 '16 at 22:59

I think you are doing right, You can check this using regex . If it returns null then it means it is not json.

if (response.headers['Content-Type'].match(/application\/json/i)){

   // do your stuff here
}

Other way is to find application/json string in header string

if (response.headers['Content-Type'].contains('application/json')){

   // do your stuff here
}

spacether · Answer 3 · 2022-09-06T18:43:01.010

There are many json content types that don't begin with application/json. See 24 of them here. One example is application/geo+json

The regex /application\/[^+]*[+]?(json);?.*/ captures all of those and the vanilla application/json with or without charset information.

It works for:

application/json
application/json; charset=UTF-8
application/json-patch+json
application/geo+json

Per:

console.log("application/json".match(/application\/[^+]*[+]?(json);?.*/)[1])
console.log("application/json; charset=UTF-8".match(/application\/[^+]*[+]?(json);?.*/)[1])
console.log("application/json-patch+json".match(/application\/[^+]*[+]?(json);?.*/)[1])
console.log("application/geo+json".match(/application\/[^+]*[+]?(json);?.*/)[1])

score 0 · Answer 4 · edited May 23 '17 at 12:09

0

There are multiple JSON content-types. Not all of them are "official", but if you are trying to match them all, try this regex:

^((application\/json)|(application\/x-javascript)|(text\/javascript)|(text\/x-javascript)|(text\/x-json))(;+.*)*$

You can add / delete content types from the regex, just remember to put proper parenthesis around them.

edited May 23 '17 at 12:09

Community

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answered Jun 25 '16 at 23:02

Jezor

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A better refactoring would be `^(application\/(json|x-javascript)|text\/(x-)?javascript|x-json)(;.*)?$`. The slashes don't need to be escaped for the regex to be correct, but if your language uses slashes as regex separators, you do need the backslashes for that reason. – tripleee Jun 30 '16 at 07:56

Regular expression to check for content type application/json etc

4 Answers4