老师关于3-15的练习

<!doctype html>
<html>
<head>
    <title></title>
    <meta http-equiv="content-type" content="text/html;charset=UTF-8"/>
    <style type="text/css">
    *{margin:0;padding:0;}
        .one{
            width:600px;
            margin:200px auto;
            border:1px dashed red;
            line-height:2em;
            text-align:center;
            color:blue;
            font-size:12px;
            font-family:"宋体",serif;
            background-color:#ccc;
            pading:5px;
            border-radius:6px;
            opacity:0.7;
        }
    </style>
    <script type="text/javascript">
        document.write('<div class="one">');
            var a=prompt('输入一段英文'),
                b='J',
                c=0,
                e=1,
                f='Javascript';
            while(true){
                if(a[c]==b){
                    if(a.substr(c,10)===f){
                        document.write(f+'第'+e+'次出现时在'+c+'的位置'+'<br/>');
                        e++;
                    }
                }else if(c==a.length){
                        document.write(f+'在这段话中出现了'+(e-1)+'次');
                        break;
                    }
                c++;
            }
        document.write('</div>')
    </script>
</head>
<body></body>
</html>

慕神6715844 2018-07-16

源自：JavaScript内置对象 3-15 编程练习