獲取倒計時之前，我們不妨先來看怎樣獲取當前時間吧！！！

function time(){
            var oDate = new Date();
            var year = oDate.getFullYear();
            var month = oDate.getMonth() + 1     ;
            var dDate = oDate.getDate();
            var day = oDate.getDay();
            var house = oDate.getHours();
            var minu = oDate.getMinutes();
            var sec = oDate.getSeconds();
            
            
            switch(day){
                case 1:
                day = '星期一';
                break;
                case 2:
                day = '星期二';
                break;
                case 3:
                day = '星期三';
                break;
                case 4:
                day = '星期四';
                break;
                case 5:
                day = '星期五';
                break;
                case 6:
                day = '星期六';
                break;
                case 0:
                day = '星期日';
                break;
            }
            
            function double( t ){
                if( t < 10 ){
                    t = '0' + t;
                }
                return t;
            }
            
            
            document.body.innerHTML = year + '年' + month +'月'+ dDate + '日  ' + day + ' ' + double(house) +':'+ double(minu) +':' + double(sec);
        }
        time();
        setInterval(time,1000);

獲取倒計時

1、實現倒計時功能
2、倒計時結束按鈕可被點擊，之前不可被點擊

<div id="lastTime">
    <span>0天 </span>
    <span>00: </span>
    <span>00: </span>
    <span>00 </span>
</div>
<br /><br />
#btn{
    text-decoration: none;
    display: block;
    width: 100px;
    height: 35px;
    background: #ccc;
    text-align: center;
    line-height: 35px;
    color: #666;
}
#btn.btn{
    background: red;
    color: #fff;
    font-size: 20px;
    font-weight: bold;
}
<a href="javascript:;" id="btn">即將開搶!</a>
<script type="text/javascript">
    var oLt = document.getElementById("lastTime");
    var oBtn = document.getElementById("btn");
    time();
    var timer = setInterval( time , 1000 );
    function time(){
        var endTime = new Date('2016/10/01 00:00:00');
        var nowTime = new Date();
        var splus = endTime.getTime() - nowTime.getTime();
        //天 時 分 秒
        if( splus <= 1 ){
            clearInterval( timer );
            oBtn.className = 'btn';
            oBn.innerHTML = '開始秒殺!';
            oBtn.;
            return;
        }else{
            oBtn.className = '';
        }
        var day = Math.floor( splus / 1000 / 60 / 60 / 24 );
        var hours = Math.floor( splus / 1000 / 60 / 60 % 24 );
        var min = Math.floor(splus / 1000 / 60 % 60);
        var sec = Math.floor(splus / 1000 % 60);
        oLt.innerHTML = day + '天 ' + double( hours ) + ':' + double( min ) + ':' + double( sec );
                
        function double( n ){
            if( n < 10 ){
                n = '0' + n;
            }
            return n;
        }
    }
</script>

效果圖如下：

Paste_Image.png