JavaScript201708/FREE/WEEK2/FREE5/2-code.html at master · yincf/JavaScript201708 · GitHub

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<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>验证码</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .codeBox {
            margin: 20px auto;
            width: 100px;
            height: 35px;
            line-height: 35px;
            font-size: 18px;
            background: lightcoral;
            text-align: center;
            cursor: pointer;
        }
    </style>
</head>
<body>
<div class="codeBox" id="codeBox"></div>

<script>
    var codeBox = document.getElementById('codeBox');

    /*
     * 思路一：杜伟民思想
     *   每一次在这个范围中获取字符,都看看现有获取的结果中是否包含这个字符,如果已经包含了,本次获取作废,重新在获取一个(具体获取多少次才能得到四位验证码不清楚)
     */
    //    function queryRandomCode() {
    //        var codeArea = '0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM';
    //        var result = '';
    //        for (var i = 0; i < 4; i++) {
    //            var ran = Math.round(Math.random() * 61);
    //            var cur = codeArea[ran];
    //            //->验证当前获取的字符,是否在现有RESULT中重复
    //            if (result.indexOf(cur) !== -1) {
    //                //->没找到合适的当前这轮的循环作废,重新在获取一个字符即可
    //                i--;
    //                continue;
    //            }
    //            result += cur;
    //        }
    //
    //        codeBox.innerHTML = result;
    //    }

    //    function queryRandomCode() {
    //        var codeArea = '0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM';
    //        var result = '';
    //        for (var i = 0; i < 4;) {
    //            var ran = Math.round(Math.random() * 61);
    //            var cur = codeArea[ran];
    //            if (result.indexOf(cur) === -1) {
    //                result += cur;
    //                i++;
    //            }
    //        }
    //
    //        codeBox.innerHTML = result;
    //    }

    function queryRandomCode() {
        var codeArea = '0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM';
        var result = '';
        while (result.length < 4) {
            var ran = Math.round(Math.random() * 61);
            var cur = codeArea[ran];
            if (result.indexOf(cur) === -1) {
                result += cur;
            }
        }
        codeBox.innerHTML = result;
    }
    queryRandomCode();
    codeBox.onclick = queryRandomCode;


    /*while (条件){
     //->条件成立就执行
     }
     while(1===1){

     } =>死循环
     */
</script>
</body>
</html>