JQuery ajax call default timeout value

As an aside, when trying to diagnose a similar bug I realised that jquery's ajax error callback returns a status of "timeout" if it failed due to a timeout.

Here's an example:

$.ajax({
    url: "/ajax_json_echo/",
    timeout: 500,
    error: function(jqXHR, textStatus, errorThrown) {
        alert(textStatus); // this will be "timeout"
    }
});

Here it is on jsfiddle.

there is no timeout, by default.

The XMLHttpRequest.timeout property represents a number of milliseconds a request can take before automatically being terminated. The default value is 0, which means there is no timeout. An important note the timeout shouldn't be used for synchronous XMLHttpRequests requests, used in a document environment or it will throw an InvalidAccessError exception. You may not use a timeout for synchronous requests with an owning window.

IE10 and 11 do not support synchronous requests, with support being phased out in other browsers too. This is due to detrimental effects resulting from making them.

More info can be found here.

In jQuery the default timeout is 0 milliseconds — which actually means “no timeout at all.”
If you don’t set the timeout option yourself (either in the options object you pass to $.ajax() or globally with $.ajaxSetup()), jQuery will leave the request open until:

1. the server responds, or

2. the browser/network layer itself decides to abort the underlying HTTP request (each browser has its own longer-running limits).

So, if a caller is seeing a request “time out” while you can’t reproduce it, the culprit is probably either:

• a custom timeout value set elsewhere in the code (check global $.ajaxSetup calls and per-request settings), or

• a server/network issue that makes the browser’s own connection timer kick in, not jQuery’s.

To impose an explicit limit, just add (for example) timeout: 15000 for 15 seconds:

$.ajax({   
    url: "/api/data",   
    method: "GET",   
    timeout: 15000,   // 15 seconds   
    success: handleSuccess,   
    error: handleError 
});