6碼驗證碼

0與O、數字1與小寫字母l、大寫字母i，容易造成使用者混淆，來源字串中應移除。

<body>

<h1>隨機抽簽1到9號不重複+產生驗證碼</h1>

<label id="number" style="color: #ff0000;font-size: 36px;">抽到的數字</label><br>

<button id="captcha" style="color: #00abff;font-size: 30px;" onclick="generateCaptcha(6)">產生驗證碼</button><br>

<label id="captchaCodes" style="font-size: 20px;">必須包含數字與大寫英文字母</label>

</div>

</body>

function generateCaptcha() {

const length = 6;

const characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';

let captchaCode = '';

for (let i = 0; i < length; i++) {

const randomIndex = Math.floor(Math.random() * characters.length);

captchaCode += characters.charAt(randomIndex);

}

const captchaElement = document.getElementById('captchaCodes');

captchaElement.textContent = captchaCode;

}

function generateCaptcha(codes) {

const length = codes;

const characters = '123456789ABCDEFGHIJKLMNPQRSTUVWXYZ';

let captchaCode = '';

while (captchaCode.length < 6){

const randomIndex = Math.floor(Math.random() * characters.length);

var tmpChar = characters.charAt(randomIndex);

var exist = false;

for (var i=0; i<captchaCode.length ;i++){

if (tmpChar===captchaCode.charAt(i)){

exist = true;

break;

}

if (!exist){

captchaCode += tmpChar;

}

const captchaElement = document.getElementById('captchaCodes');

captchaElement.textContent = captchaCode;

}