[CLA] - Syntax error with xhrGet and JSON handling with 20x and no content

[Chris Mitchell]

I am calling dojo.xhrGet with handleAs: "json-comment-optional" and the service is giving back "". which is causing

dojo.fromJson = function(/*String*/ json){
	// summary:
	// 		Parses a [JSON](http://json.org) string to return a JavaScript object.
	// json: 
	//		a string literal of a JSON item, for instance:
	//			`'{ "foo": [ "bar", 1, { "baz": "thud" } ] }'`
	return eval("(" + json + ")"); // Object
}

In 20x responses with no content, json is "", resulting in the handler throwing a syntax error. Throwing a syntax error with no content is not correct behavior, and it previously worked in 1.0.x.

To fix the problem, we're running with the following patch to the above function in dojo/_base/xhr.js:

return json==="" ? "" : eval("("+json+")");

This patch is submitted under CCLA by Chris Mitchell.

Can we get this in for 1.1.1?

[Adam Peller]

return undefined when xhr results in a 204

[Adam Peller]

So I don't think we should allow an empty string in fromJson, since it's not valid. We can special case in xhr for json, but probably only for http error 204, where an empty content type is required, and in that case we still wouldn't want to pass back "" or anything which might be a valid JSON return type, because you couldn't tell the difference. We could return 'undefined', or just throw an exception, which the caller could handle and inspect the thrown error object for status. The attached patch returns undefined. Thoughts?

[Adam Peller]

(In [13457]) Return undefined for JSON requests with HTTP Status 204, rather than throw, since it's successful by definition. Fixes #6601 Fix typo in dojo.query comments and style of assignments in conditionals. !strict

[Adam Peller]

(In [13458]) Return undefined for JSON requests with HTTP Status 204, rather than throw, since it's successful by definition. (1.1 branch) Refs #6601