JS实现倒计时代码实例

var count = 60 * 15;
var countdown = setInterval(CountDown, 1000);
function CountDown() {
    if (count >= 0) {
        var minutes = Math.floor(count / 60);
        var seconds = Math.floor(count % 60);
        var msg = "请等待" + minutes + "分" + seconds + "秒";
       alert(msg)
        --count;
    } else {
        clearInterval(countdown);
       alert("倒计时结束")
    }
}