函数节流

function fn(){}
var throttle=function(fn,delay)
{
var timer=null;
return function()
{
var context=this,args=arguments;
clearTimeout(timer);
timer=setTimeout(function()
{
fn.apply(context,args);
console.log(context);//input
console.log(this);//window
},delay);
};
};
var btn=document.getElementById('my-btn');
btn.addEventListener('click',throttle(fn,50),false);