How can I use Modernizr to test a browser for AJAX support?

Question

As a big fan of Progressive-Enhancement, I use Modernizr to test browser capabilities. How can I use Modernizr to test the browser's support of AJAX (specifically, jQuery's AJAX functions)?

Answer 1

You don't need Modernizer to test this, jQuery has it built-in.

if (jQuery.support.ajax) {
    alert("Ajax is supported!");
}

Although i'm not sure exactly how jQuery handles $.ajax calls when it isn't supported. It will either fail silently, or trigger the error callback. If it's important to you, you should test it.

Answer 2

For what it's worth, I have added issue #734 to Modernizr to add a test for AJAX, developed the test, created a JSFiddle to test, er, the test...and initiated a pull-request (issue #735) back to the fine folks who maintain Modernizr.

The relevant JS:

Modernizr.addTest('ajax', function() {
    var xhr = new XMLHttpRequest();
    return !!('onreadystatechange' in xhr);
});