使用setInterval模拟setTimeout:
执行一次setInterval然后清除即可
function mySetTimeout(fn, t){
    let timer = setInterval(()=>{
        fn();
        clearInterval(timer)
    },t)
}
let a = mySetTimeout(()=>{
    console.log('xxx')
},1000)
使用setInterval模拟setTimeout:
执行一次setInterval然后清除即可
function mySetTimeout(fn, t){
    let timer = setInterval(()=>{
        fn();
        clearInterval(timer)
    },t)
}
let a = mySetTimeout(()=>{
    console.log('xxx')
},1000)