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How to implement front-end verification code in js? (code)

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不言Original
2018-08-15 15:55:331950browse

The content of this article is about how to implement the front-end verification code in js? (code), it has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Students who can check this knowledge point must have at least mastered a little bit of JavaWeb knowledge. They should be able to understand this code and know how to use it! 

<body>
  <div class="input">
            &nbsp&nbsp<span 
style="font-size:16px;font-family: 
黑体">验证码:</span>&nbsp<input id="t1" type="text" name="u" 
 onblur="but()" />
                   <span id="discode"></span>
                   <input type="button" value="点击刷新" class="c" style="height:20px;"onClick="createCode()">
      </div>
<script language="javascript">
        var code; //在全局 定义验证码
        function createCode() { //创建验证码函数
            code = "";
            var codeLength = 4;//验证码的长度
            var selectChar = new Array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, &#39;A&#39;, &#39;B&#39;,
                    &#39;C&#39;, &#39;D&#39;, &#39;E&#39;, &#39;F&#39;, &#39;G&#39;, &#39;H&#39;, &#39;I&#39;, &#39;J&#39;, &#39;K&#39;, &#39;L&#39;, &#39;M&#39;, &#39;N&#39;,
                    &#39;O&#39;, &#39;P&#39;, &#39;Q&#39;, &#39;R&#39;, &#39;S&#39;, &#39;T&#39;, &#39;U&#39;, &#39;V&#39;, &#39;W&#39;, &#39;X&#39;, &#39;Y&#39;, &#39;Z&#39;);//所有候选组成验证码的字符，当然也可以用中文的
            for (var i = 0; i < codeLength; i++) {
                var charIndex = Math.floor(Math.random() * 36);
                code += selectChar[charIndex];
            }
            // 设置验证码的显示样式，并显示
            document.getElementById("discode").style.fontFamily = "黑体"; //设置字体
            document.getElementById("discode").style.letterSpacing = "20px"; //字体间距
            document.getElementById("discode").style.color = "red"; //字体颜色
            document.getElementById("discode").innerHTML = code; // 显示
        }
        function but() {//验证验证码输入是否正确
            var val1 = document.getElementById("t1").value;
            var val2 = code;
            if (val1 != val2) {
                
                document.getElementById(&#39;t1&#39;).value = "";
            }
        }
    </script>
</body>

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