定时器

用setTimeout 实现setInterval

let timers = [];
let i = 0;
function mySetInterval(callback, time) {
    let j = i;
    function main() {
        timers[j] = setTimeout(() => {
            callback();
            main();
        }, time)
    }
    
    main();
    i++;
    return j;
}

function myClearInterval(intervalId) {
    clearTimeout(timers[intervalId]);
}

let timer1 = setInterval(() => console.log('timer1'), 3000)
let timer2 = setInterval(() => console.log('timer2'), 3000)

console.log(timer1, timer2);