javascript实现数字+字母验证码的简单实例_javascript技巧

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','wW','x','y','z');//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 {

var charIndex = Math.floor(Math.random()*36);
code +=selectChar[charIndex];

}
// alert(code);
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！");
}
else if(inputCode != code )
{
alert("验证码输入错误！");
createCode();//刷新验证码
}
else
{
alert("OK");
}

}