function debounce(func,wait,immediate){
    var timeout;
    return function() {
        var context=this,args=arguments;
        var later=function(){
            timeout=null;
            if(!immediate) func.apply(context,args);
        }
        var callNow=immediate && !timeout;
        clearTimeout(timeout);
        timeout=setTimeout(later,wait);
        if(callNow) func.apply(context,args);
    };
};
var myEfficientFn = debounce(function(){
    console.log("Success");
},500);
window.addEventListener("scroll",myEfficientFn);

比如上面这段函数