Detect if callback is called

gistfile1.js

function doTest (callback) {
    var isCallbackCalled = false;

    var successCallback = function () {
        isCallbackCalled = true;
    };

    callback.apply(null, [ successCallback ]);

    if (isCallbackCalled) {
        alert('Callback called');
    }
    else {
        alert('Callback not called');
    }
}

doTest(function (callback) {
    alert('Test 1, callback called!');
    callback();
});
doTest(function(callback) {
    alert('Test 2, callback not called');
});