“21天好习惯”第一期-1 JavaScript实现倒计时

 先创建一个名叫time的div

 CSS样式：

.time{
	background: skyblue;
	width: 367px;
	height: 300px;
	text-align: center;
	margin: auto;
	font-size: 30px;
}

Javascript;

var str = prompt('请输入时间');
var time1= setInterval(function(){
	var newtime = new Date();
	var now = newtime.getTime();
	var endtime = new Date(str);
	var end = endtime.getTime();
	var time = end - now;
	var timebox = document.querySelector('.time');
	var d,h,m,s;
	d = Math.floor(time/1000/60/60/24);
	h = Math.floor(time/1000/60/60%24);
	m = Math.floor(time/1000/60%60);
	s = Math.floor(time/1000%60);
	if(time>1){
		timebox.innerHTML = "距离"+str+"还剩："+d+"天"+h+"小时"+m+"分钟"+s+"秒";
	}
	else{
		timebox.innerHTML = str+"已经到了";
	}
},1000);