lovecoding
/
web0715


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            width: 300px;
            height: 300px;
            background-color: #aaa;
            box-shadow: 0 0 10px rgba(0,0,0,.5);
            border-radius: 10px;
            position: fixed;
            top:50%;
            left:50%;
            margin-left: -150px;
            margin-top: -150px;
            text-align: center;
            line-height: 300px;
            font-size: 40px;
            font-weight: 500;
        }
    </style>
</head>
<body>
    <div class="box">
        <span>10</span>
    </div>
    <script>
        var oSpan = document.getElementsByTagName("span");
        var num = 10;

        var setObj = setInterval(function(){
            if(num == 0){
                clearInterval(setObj);
            }
            oSpan[0].innerText = num--;
        },1000);
       
       
       
        // oSpan[0].innerText = "hello world";

        // var arr = [1,2,3,4]
        // arr[0] = "a"
    </script>
</body>
</html>