js如何实现函数防抖与节流

 <div>
    <div>
        <input type="text" id="unDebounce">
    </div>
    <div>
        <input type="text" id="debounce">
    </div>
    <div>
        <input type="text" id="throttle">
    </div>
</div>

// 函数防抖节流
var elem1 = document.getElementById("unDebounce")
var elem2 = document.getElementById("debounce")
var elem3 = document.getElementById("throttle")
// 不防抖
function ajax1(value){
    console.log("不防抖，不节流")
    console.log(value)
}
elem1.addEventListener('keyup',function (e) {
    ajax1(e.target.value);
})
// 防抖
function ajax2(value) {
    console.log(value)
}
function debounce(func,delay){
    console.log("函数防抖")
    let timer = null;
    return function(...args){
        if(timer){
            console.log("清除定时器")
            clearTimeout(timer)
        }
        timer = setTimeout(()=>{
            console.log("重新计时")
            func.call(this,...args)
        },delay)
    }
}
let debounceFn = debounce(ajax2,1000)
elem2.addEventListener('keyup',function (e) {
    debounceFn(e.target.value);
})
// // 节流
function ajax3(value){
    console.log(value)
}
function throttle(func,delay){
    console.log("函数节流")
    let lastTime = 0;
    let timer = null;
    return function (...args) {
        let flag = false ; // 还没发送数据
        let now = +new Date().getTime();
        if(timer){
            clearTimeout(timer)
        }
        if(now-lastTime>=delay){
            console.log("当前时间大于设定时间，开始执行函数")
            func.apply(this,args)
            console.log("time1",new Date().getTime())
            lastTime = now;
            flag = true; // 发送了数据
        }else{
            timer = setTimeout(()=>{
                if(!flag){ // 如果没有发送数据成功，再走这个，兜底发送请求
                    func.apply(this,args)
                    console.log("time2",new Date().getTime())
                }
            },delay-(now-lastTime)+1000) // setTimeout多一些，优先执行周期性请求
        }
    }
}
let throttleFn = throttle(ajax3,5000)
elem3.addEventListener('keyup',function (e) {
    throttleFn(e.target.value);
})