Ajax error defaults to status 404

[hvrauhal]

In jquery 2.0.x, ajax requests that fail without ever contacting a server resolve with jqXHR.status 404 and jqXHR.readyState 4. See ​http://jsbin.com/ejeruf/9 for an example.

In 1.x versions they resolve with jqXHR.status 0 and jqXHR.readyState 0 as expected. See ​http://jsbin.com/ejeruf/4

The 2.0.x version seems to default to 404 at ​https://github.com/jquery/jquery/blob/2.0.3/src/ajax/xhr.js#L75 without checking whether the request was local and not crossdomain, as the 1.x version did in ​https://github.com/jquery/jquery/blob/1.10.2/src/ajax/xhr.js#L156

[dmethvin]

@jaubourg, thoughts?

[hvrauhal]

This buggy behaviour makes jquery 2.0 dangerous to use in modern webapps in wireless environments, where it is essential to know the difference between network errors (that should return with status 0) and real 404's returned by the server.

[hvrauhal]

I could post a patch that just removes the ' || 404 ', but that would leave the refactoring of xhr.js halfway regarding how error statuses are handled in file-protocol. The xhrSuccessStatus-mapping does not take the actual request protocol into account neither, though it appears to me that it should.

[jaubourg]

I'm afraid the only actual solution would be to add the local protocol detection code back in. That's the only way we'll be able to differentiate between a 404 and an actual network error.

Let me tag this as xhr-spec. I should really find time to have this dealt with in the XHR spec.

[jaubourg]

All right, the only solution I see here is to just remove || 404. The only bad side-effect (apart from having a 0 status code for error on local protocols) is a wrong readyState (0 rather than 4) on the jqXHR object. I can live with that.

[Dave Methvin]

ajax: Fix #14207. file protocol returns status 0, see #8605.

Changeset: dce2edb3a615f9de158607c9f8be83809373940e