javascript如何实现10秒倒计时代码

var t = 10;
var countdown = setInterval("countdownF()",1000);
function countdownF() {
  console.log('倒计时还剩' + t + '秒')
  if (t == 0) {
    clearInterval(countdown);
    console.log("10s倒计时结束！")
  }
  t--;
}