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JavaScript automatically generates dynamic HTML verification code

陈政宽～Original: 2017-06-28 12:40:483486browse

This article mainly introduces JS to automatically generate dynamic HTMLVerification code page, and the function of automatically clearing the input box when inputting errors. It has certain reference value. Interested friends can refer to it

This article shares with you the JS automatically generated dynamic HTML verification code page, the function of automatically clearing the input box when inputting errors, for your reference, the specific content is as follows

<!DOCTYPE html>
<html>
<head>
 <title>验证码</title>
<meta charset="utf-8" />
<style type="text/css">
 #code {
  font-family: Arial;
  font-style: italic;
  font-weight: bold;
  border: 0;
  letter-spacing: 2px;
  color: blue;
 }
</style>
<script>
 //产生验证码 
 window.onload = function() {
  createCode()
 }
 var code; //在全局定义验证码 
 function createCode() {
  code = "";
  var codeLength = 4; //验证码的长度 
  var checkCode = document.getElementById("code");
  var random = 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;); //随机数 
  for(var i = 0; i < codeLength; i++) { //循环操作 
  var index = Math.floor(Math.random() * 36); //取得随机数的索引（0~35） 
   code += random[index]; //根据索引取得随机数加到code上 
  }
  checkCode.value = code; //把code值赋给验证码 
 }
 //校验验证码 
 function validate() {
 var inputCode = document.getElementById("ctl00_txtcode").value.toUpperCase(); //获取输入框内验证码并转化为大写  
 if(inputCode.length <= 0) { //若输入的验证码长度为0 
  alert("请输入验证码！"); //则弹出请输入验证码 
 } 
 else if(inputCode != code) { //若输入的验证码与产生的验证码不一致时 
  alert("验证码输入错误!"); //则弹出验证码输入错误 
  createCode(); //刷新验证码 
  document.getElementById("ctl00_txtcode").value = "";//清空文本框 
 } else { //输入正确时 
  alert("正在登陆"); //弹出 
  }
 }
</script>
</head>
<body>
 <p>
   <!--时间：2017-01-11 描述：输入框ct100_textcode -->
   <input type="text" id="ctl00_txtcode" />
   <!--时间：2017-01-11 描述：把验证码定义为按钮，点击刷新-->
   <input type="button" id="code" onclick="createCode()" />
   <!--时间：2017-01-11 描述：验证按钮 -->
   <input type="button" value="验证" onclick="validate()" />
  </p>
 </body
</html>

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