1.防抖

触发事件后在n秒内函数只执行一次，如果在n秒内又触发了事件，则会重新计算时间

<button id="btn">点击</button>
    <script>
        function fun (fn,awaits){
            var times = null
            return function(){
                let This = this
                if(times) {
                    clearTimeout(times)
                }
                times = setTimeout(function(){
                    fn.apply(This,arguments)
                    times = null
                },awaits)
            }
        }

        let btn = document.getElementById('btn')
        function a (){
            console.log('123')
        }
        btn.onclick = fun(a,1000)
    </script>

节流

触发事件，但是在n秒内只执行一次

<button id="btn">点击</button>
    <script>
        function fun (fn,awaits){
            var times = null
            return function(){
                let This = this
                if(times) return 
                times = setTimeout(function(){
                    fn.apply(This,arguments)

                    // console.log(times)
                    times = null
                },awaits)
            }
        }

        let btn = document.getElementById('btn')
        function a (){
            console.log('123')
        }
        btn.onclick = fun(a,3000)
    </script>