版本1.0

function throttle (fn,delay) {
            var delay = delay || 1000;
            var lastTime = 0;
            function newFn () {
              if(new Date().getTime() - lastTime >= delay){
                return fn.apply(this,arguments);
                lastTime = new Date().getTime();
              }
            }
            return newFn;
          }

版本2.0
原型链上封装

Function.prototype.throttle = function (delay) {
            var fn = this;
            var lastTime = 0;
            function newFn () {
              if(new Date().getTime() - lastTime >= delay){
                return fn.apply(this,arguments);
                lastTime = new Date().getTime();
              }
            }
            return newFn;
          }

版本3.0
这种需求应该很少.
能够new实现继承,

Function.prototype.throttle = function (delay) {
            var fn = this;
            var lastTime = 0;
            newFn.prototype = fn.prototype;// 这里可用圣杯继承代替.
            function newFn () {
              if(new Date().getTime() - lastTime >= delay){
               return fn.apply(this,arguments);
                lastTime = new Date().getTime();
              }
            }
            return newFn;
          }