javascript实现验证码功能

以你之姓@ 2022-03-26 01:06 414阅读 0赞

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
        <style>
            #code{
                font-family:Arial;
                font-style:italic;
                font-weight:bold;
                border:0;
                letter-spacing:2px;
                color:blue;
            }
        </style>
    </head>
    <body>
    <div>
        <input type = "text" id = "input" value="" />
        <input type = "button" id="code" onclick="createCode()"/>
        <input type = "button" value = "验证" onclick = "validate()"/>
    </div>
    <script>
        //设置一个全局的变量，便于保存验证码
        var code;
        function createCode(){
            //首先默认code为空字符串
            code = '';
            //设置长度，这里看需求，我这里设置了4
            var codeLength = 4;
            var codeV = document.getElementById('code');
            //设置随机字符
            var random = 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');
            //循环codeLength 我设置的4就是循环4次
            for(var i = 0; i < codeLength; i++){
                //设置随机数范围,这设置为0 ~ 36
                var index = Math.floor(Math.random()*36);
                //字符串拼接 将每次随机的字符 进行拼接
                code += random[index];
            }
            //将拼接好的字符串赋值给展示的Value
            codeV.value = code;
        }
    
        //下面就是判断是否== 的代码，无需解释
        function validate(){
            var oValue = document.getElementById('input').value.toUpperCase();
            if(oValue ==0){
                alert('请输入验证码');
            }else if(oValue != code){
                alert('验证码不正确，请重新输入');
                oValue = ' ';
                createCode();
            }else{
               alert("验证码正确");
            }
        }
    
        //设置此处的原因是每次进入界面展示一个随机的验证码，不设置则为空
        window.onload = function (){
    
            createCode();
        }
    </script>
    </body>
    </html>