防抖:多次触发后执行一次
节流:多次触发只在规定时间内执行一次

 //防抖
        function debounce(func,await){
            let timeout
            return function(){
                let content = this
                let args = arguments

                if(timeout) clearInterval(timeout)
                timeout = setTimeout(()=>{
                    func.apply(content,args)
                },await)
            }
        }

        //节流
        function throttle(func,await){
            let previous = 0
            return function(){
                let now = Date.now()
                let context = this
                let args = arguments
                if(now-previous>await){
                    func.apply(context,args)
                    previous = now
                }
            }
        }