js倒计时小功能

function timeD(){
    var num=$(".goTel").text()-0;
    console.log(num);
    num--;
    if(num==0 || isNaN(num)){
        console.log('进来了');
        $(".goTel").html('发送');
        clearTimeout(t)
    }else{
        $(".goTel").text(num);
    }
}
  t = setInterval(timeD,1000)