#13431 is a duplicate of this ticket.

Thanks for taking the time to contribute to the jQuery project! Please provide a complete reduced test case on jsFiddle to help us assess your ticket!

Additionally, be sure to test against the "jQuery (edge)" version to ensure the issue still exists—you may need to change this to a specific version depending on the test case.

To get you started, use this boilerplate: http://jsfiddle.net/FrKyN/ Open the link and click to "Fork" (in the top menu) to begin.

Also, please read: http://blog.jquery.com/2013/01/15/jquery-1-9-final-jquery-2-0-beta-migrate-final-released/

It's really as simple as typing

$.parseJSON("");

or

$.parseJSON(undefined);

in web console (of Chrome 24.0.1312.57 m or Firefox 21.0a1, both on Windows in my case).

Edge and 1.9.0 are affected.

Ok then, there is your problem. An empty string or undefined are not valid JSON. The jQuery Migrate plugin catches these things for you, and will even fix them if you don't want to change code right now:

https://github.com/jquery/jquery-migrate/blob/master/warnings.md#jqmigrate-jqueryparsejson-requires-a-valid-json-string

Ok, but API docs still state:

"Additionally if you pass in nothing, an empty string, null, or undefined, 'null' will be returned from parseJSON."

Which is kind of misleading.

Agreed. There's a docs ticket open to fix that. Note that it does say the method takes a string, and that it takes a JSON string. Unfortunately someone documented the incorrect behavior at some point.

#13630 is a duplicate of this ticket.

Is not bug jQuery.

if ( window.JSON && window.JSON.parse ) {
	JSON.parse_original = JSON.parse;
	JSON.parse = function(data){
		return (data == "") ? {} : JSON.parse_original(data);
	}
}

#14360 is a duplicate of this ticket.

Duplicate of #13169.