簡單的驗證碼登入功能的實作
<html>
<head>
<style>
#code{
font-family:Arial;
font-style:italic;
font-weight:bold;
border:0;
letter-spacing:2px;
color:blue;
}
</style>
<script>
//生成驗證碼的JS
var code;
function createCode(){
//生成驗證碼
code = '';
//設定驗證碼的長度為4
var codeLength = 4;
var codeV = document.getElementById('code');
//随機函數生成驗證碼
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');
for(var i = 0; i < codeLength; i++){
//取得随機數的索引（0-35）
var index = Math.floor(Math.random()*36);
//根據索引取得随機數加到code上
code += random[index];
}
//把code值賦給驗證碼
codeV.value = code;
}
//校驗驗證碼
function validate(){
var oValue = document.getElementById('input').value.toUpperCase();
if(oValue ==0){
alert('請輸入驗證碼');
}else if(oValue != code){
alert('驗證碼輸入有誤');
document.getElementByID('input').value="";//清空文本框
oValue = ' ';
//重新生成驗證碼
createCode();
}else{
alert("驗證碼正确");2018/4/4
}
}
//加載頁面的同生成驗證碼并顯示
window.onload = function (){
createCode();
}
</script>
</head>
<body>
<div>
<input type = "text" id = "input" value="" />
<input type = "button" id="code" οnclick="createCode()"/>
<input type = "button" value = "驗證" onclick = "validate()"/>
</div>
</body>
</html>
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