节流 防抖

//节流 设置的时间内只能调用一次
//节流函数 写法1 时间差版本
function throttle(method, delay) {
    let timer,
        args = arguments,
        start;
    return function fn() {
        let self = this;
        let now = Date.now();
        if(!start){
            start = now;
        }
        if(timer){
            clearTimeout(timer);
        }
        if(now - start >= delay){
            method.apply(self, args);
            start = now;
        }else {
            timer = setTimeout(function () {
                console.log(args,'args')
                fn.apply(self, args);
            }, delay);
        }
    }
}

//节流函数 写法2 定时器版本

function throttle(fn,delay) {

    var executed = false

    return function () {

        if(executed) return;

        var that = this;

        

        fn.apply(that,...arguments)

        executed = true

        

        setTimeout(() => {

            executed = false;

        }, delay);

    }

}

// 防抖函数
function debounce(method,delay){
        let _delay = delay || 0;

        let timer = null;

        return function(){
            let args = arguments;


            timer && clearTimeout(timer);

            timer = setTimeout(()=>{
                method.apply(this,args)
            },_delay)
        }

      }

 这里用的apply和call主要改变this指向。