• setTimeout: 倒计时后一次调用
• setInterval: 间隔时间之间重复调用

// 方法一：递归套娃，套娃结束的时候，只是clearInterval是通过返回的属性设置
const setTimeoutToInterval = (fn, timeout) => {const timer = { flag: true };const interval = () => {if (timer.flag) {fn();setTimeout(interval, timeout);}};setTimeout(interval, timeout);return timer;
};
const fn = () => console.log("------interval------");
const curTimer = setTimeoutToInterval(fn, 1000);
setTimeout(() => {curTimer["flag"] = false;
}, 6000);//   方法二：递归——直接套娃，本质和方法一并无二致
const _setTimeoutToInterval = (fn, timeout, times) => {if (!times) return;setTimeout(() => {fn();_setTimeoutToInterval(fn, timeout, --times);}, timeout);
};//   方法三：递归——具名回调函数 + clearTimeout
const __setTimeoutToInterval = (fn, timeout, times) => {let timer = setTimeout(function aa() {fn();timer--;timer = setTimeout(aa, timeout);if (times <= 0) {clearTimeout(timer);}}, timeout);
};