如何制作min：sec倒计时器

Question

这段代码有什么问题？它没有在页面上显示一个计时器，当我在JSFiddle中测试它时，我得到一个“输入结束”语法错误。

$( engage ).click(function () {
 setTimeout(function () {
                    var timeDisplay = document.createElement("p");
                    clock.appendChild(timeDisplay);

                    while (true) {
                        var target = 50 * 60;
                        var curr = target;

                        var x = setInterval(function () {
                            curr -= 1;

                            var mins = Math.floor(curr / 60);
                            var secs = curr % 60;
                            if (secs < 10) {
                                secs = "0" + secs;
                            }

                            console.log(mins + ":" + secs);
                            timeDisplay.innerHTML = mins + ":" + secs;
                        }, 1000);
                    }
                }, 500);

Answer 1

好的，所以你做了以下，但我无法理解你想要做什么。我建议你重命名变量，让自己更好地理解代码。

$( engage ).click(function () {
 setTimeout(function () {
                    var timeDisplay = document.createElement("p");
                    clock.appendChild(timeDisplay);

                    while (true) {
                        var target = 50 * 60;
                        var curr = target;

                        var x = setInterval(function () {
                            curr -= 1;

                            var mins = Math.floor(curr / 60);
                            var secs = curr % 60;
                            if (secs < 10) {
                                secs = "0" + secs;
                            }

                            console.log(mins + ":" + secs);
                            timeDisplay.innerHTML = mins + ":" + secs;
                        }, 1000);
                    }
                }, 500);

我有以下工作代码：

function startTime() {
    var today = new Date();
    var h = today.getHours();
    var m = today.getMinutes();
    var s = today.getSeconds();
    m = checkTime(m);
    s = checkTime(s);
   

 console.log(h + ":" + m + ":" + s);
    var t = setTimeout(startTime, 500);
}
function checkTime(i) {
    if (i < 10) {i = "0" + i};  // add zero in front of numbers < 10
    return i;
}