javascript - 为什么输出中递减后不显示零？这是超时程序

Question

这是我的代码的链接 http://codepen.io/meow414/pen/adLoEY请看一下。当 sec=0 时，sec 变量不显示 0，它在 sec==0 时执行，但递减后不显示 0？如何显示它。

var min = 0;
var sec = 3;
var over;

function xyz() {
    document.getElementById("abc").innerHTML = min + ":" + sec;

    sec--;    //it is getting decremeted upto 0,that's why below while loop is running bu in output zero is not shown for ex 3 after decrementing will show like 3 then 2 then 1 then it will chnage to 9.

    while(sec == 0) {
        sec = 9;
    }
}

$("#start").click(function() {
    over=setInterval(xyz, 1000);
});

$("#pause").click(function() {
    clearInterval(over);
});

$("#reset").click(function() {
    min = 0;
    sec = 5;
    clearInterval(over);
    document.getElementById("abc").innerHTML = min + ":" + sec;
});

Answer 1

您的函数使用 while 作为条件(而不是 if)。

此外，当您将 sec 从 1 更改为 0 时，您会根据该条件立即将其设置为 9。

尝试

 function xyz() {
   // Show sec, even if it's 0
   document.getElementById("abc").innerHTML = min + ":" + sec; 
   // Then if(sec===0) set sec to 9 (the HTML will still show 0)
   if (sec === 0) {
     sec = 9;
   }
   // Otherwise, decrement sec
   else {
     sec--;
   }
 }

代码笔:http://codepen.io/anon/pen/rxGBbd