setTimeout

// from http://javascript.ruanyifeng.com/bom/engine.html#toc9
// 防抖动，只有当两次触发之间的时间间隔大于事先设定的值，这个新函数才会运行实际的任务
function debounce(fn, delay){
    var timer = null; // 声明计时器
    return function(){
        var context = this, args = arguments;
        clearTimeout(timer);
        timer = setTimeout(function(){
            fn.apply(context, args);
        }, delay);
    };
}

// from http://javascript.ruanyifeng.com/bom/engine.html#toc10
// 循环调用setTimeout模拟了setInterval，防止setInterval阻塞
function interval(func, wait){
    var interv = function(w){
        return function(){
                setTimeout(interv, w);
                    func.call(null);
        }
    }(wait);

    setTimeout(interv, wait);
}

// http://javascript.ruanyifeng.com/jquery/deferred.html#toc12
// 改写setTimeout方法，让其返回一个deferred对象
function doSomethingLater(fn, time) {
    var dfd = $.Deferred();
    setTimeout(function() {
        dfd.resolve(fn());
    }, time || 0);
    return dfd.promise();
}