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Function.prototype.waitUntil = function (condition, interval) {
    interval = interval || 100;
    
    var fn = this,
        shell = function () {
            var timer = setInterval(
                function () {
                    var check;
                    
                    try { check = !!(condition()); } catch (e) { check = false; }
                    
                    if (check) {
                        clearInterval(timer);
                        delete timer;
                        fn();
                    }
                },
                interval
            );
        };
    
    return shell;
};

(function () { window.status = 'I waited, and waited, and waited...'; }).waitUntil(function () { return !!(something === true); })();