函数防抖

export function debounce(fn, wait){
            let timeout = null;
            return function() {
                if(timeout !== null) {
                  clearTimeout(timeout);
                }
                timeout = setTimeout(fn,wait)
            }
        }

节流

 function throttler(fn,delay){
            let flag = true;
            return function(){
              if(!flag){
                return false // 休息
              }
              flag = false; // 营业
              fn();
              setTimeout(() => {
                flag = true
              }, delay)
            }
        }