简易的验证码

[javascript]代码库

<script language="javascript" type="text/javascript"> 
 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("checkCode");
  var selectChar = new Array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9,'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z');//所有候选组成验证码的字符 
  
  for (var i = 0; i < codeLength; i++) {
    var charIndex = Math.floor(Math.random() * 36);
    code += selectChar[charIndex];
  }
 
  if (checkCode) {
    checkCode.className = "code";
    checkCode.value = code;
  }
}
  
function validate() {
  var inputCode = document.getElementById("input1").value;
  if (inputCode.length <= 0) {
    alert("请输入验证码！");
	createCode();//刷新验证码 
  } else if (inputCode != code) {
    alert("验证码输入错误！");
  createCode();//刷新验证码  
  } else {
  gosubmit();
  }
}
</script>