Checking for dependancies and sending a callback when they have loaded. For use when you're expecting a library to load and you don't know when it'll appear.

utils.dependancyCheck.js

(function () {
    var utils = window.utils || {};

    utils.dependancyCheck = function (dependancies, callback) {
        dependancies = !(dependancies instanceof Array) ? [dependancies] : dependancies;

        var checkForDependancies = function () {
            var i = 0;
            for (; i < dependancies.length; ++i) {
                if (dependancies[i] !== undefined) {
                    // Remove current item from array, then step backwards. Yes I know --VAR and VAR-- differences.
                    dependancies.splice(i--, 1);
                }
                if (dependancies.length !== 0) {
                    window.setTimeout(checkForDependancies, 50);
                } else {
                    callback();
                }
            }
        };

        checkForDependancies();
    };

    window.utils = utils;
}());