Environment

OS: Mac OSX 10.6.6

Browser: FF 3.1.16

Add-ons used in testing: Firebug 1.6.2, HTTPFox 0.8.8

Problem

When using $.getJSON, in a proxied environment, you may get a 407 error, which means the proxy needs to be re-authenticated; when using $.ajax, this works fine (ie: there is no error called, and the 407 turns into a 200 after 1 second or so).

To replicate this, you will need a proxy server that can be setup to authenticate, unfortunately I don't have one to show you the error, so instead here is an example, and what I see in the firefox httpfox plugin and firebug:

getJSON - fails

var successFunc = function(r){ console.log("ok:", r); };

$.getJSON( urlThat407s, successFunc ).error( function( result ) {
    console.log( "err: ", result.status );
});

Firebug result:

err: 0

HttpFox:

Result: 407

Type: text/html (NS_ERROR_DOM_BAD_URI)

ajax - this is ok, I'm using it as a temporary workaround

var successFunc = function(r){ console.log("ok:", r); };

$.ajax( {
    url: urlThat407s,
    dataType: "jsonp",
    cache: true,
    timeout: 30000,
    success: successFunc,
    error: function( result ) {
        console.log( "err: ", result.status );
    }
} );

Firebug result:

ok: value from JSONP server

HttpFox:

Result: 200

Type: text/html

Note: HttpFox briefly flashes the 407 error, before turning into a 200

What I was expecting

Ideally $.getJSON would be able to handle the 407 just like $.ajax does, however if it has to fail, (ie: you cannot make it work like $.ajax), then at least the status should be set to 407, rather than 0