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jQuery implements click switching verification code

PHPz

May 11, 2023 pm 10:16 PM

With the rapid development of the Internet, verification codes have become an indispensable part. Whether registering, logging in, or submitting an order, we need to enter the correct verification code to continue. Today's verification codes are no longer simple numbers or letters, but more complex verification codes with pictures, sliders and other interactions.

In website development, implementing the function of verification code has also become an indispensable part. However, the verification codes of some websites are too complex and need to be refreshed constantly, which is undoubtedly a big blow to users. So, how to make the user experience better on the basis of implementing the verification code? Here, the author would like to introduce a method of using jQuery to implement click-to-switch verification codes.

We can use jQuery to achieve the effect of clicking to switch verification codes, and it is very simple and easy to understand. First, we need to know what a verification code is. Verification code is a technology that prevents robot programs from simulating human behavior. It usually consists of a string of numbers and letters and a picture. Here, the verification code we use consists of a picture and a text input box.

The following is the code implementation. If you are not familiar with jQuery, you can learn the basics of jQuery first.

HTML code:

<!DOCTYPE html>
<html>
<head>
    <title>点击切换验证码</title>
    <meta charset="utf-8">
    <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
</head>
<body>
    <div id="captcha" style="display: inline-block;">
        <img  src="/static/imghwm/default1.png"  data-src="captcha.php"  class="lazy"  id="captchaImg" onclick="changeCaptcha()" / alt="jQuery implements click switching verification code" >
    </div>
    <input type="text" id="captchaInput" />
    <button id="submitBtn">提交</button>
</body>
<script>
$(function(){
    $('#submitBtn').click(function(){
        alert('验证码输入正确！');
    });
});
</script>
</html>

In the HTML code, we define a div with the id captcha, which contains an img tag with the id captchaImg and an input tag with the id captchaInput. and a submit button. Among them, captchaImg is the verification code image, and captchaInput is the verification code entered by the user. Next, we need to implement the function of clicking to switch verification codes.

JavaScript code:

function changeCaptcha() {
    $('#captchaImg').attr({
        src: 'captcha.php?' + Math.random()
    });
}

In the JavaScript code, we refresh the verification code by changing the src attribute of the image. Note that we added a random number after the URL to avoid caching problems that would cause the verification code image to not be refreshed.

Finally, we return to the HTML code again, use jQuery to monitor the user's click event, and verify whether the verification code entered by the user is correct.

jQuery code:

$(function(){
    $('#submitBtn').click(function(){
        if ($('#captchaInput').val() != '') {
            $.post('verification.php', {captcha: $('#captchaInput').val()}, function(res){
                if (res == 'success') {
                    alert('验证码输入正确！');
                }
                else {
                    alert('验证码输入错误，请重新输入！');
                    changeCaptcha();
                    $('#captchaInput').val('');
                }
            });
        }
        else {
            alert('请输入验证码！');
        }
    });
});

In the jQuery code, we first determine whether the user has entered the verification code. If there is input, we use Ajax to verify to the server whether the verification code is correct. On the server side, we can achieve this through mechanisms such as session or cookie. Here, we use a verification.php to simulate the process of server verification of the verification code.

verification.php code:

<?php
session_start();
if ($_POST['captcha'] == $_SESSION['captcha']) {
    echo 'success';
}
else {
    echo 'fail';
}
?>

In the verification.php file, we first open the session, and then determine whether the verification code entered by the user matches the generated verification code. If they match, return success, otherwise return fail.

Based on the above code, we have implemented a function to switch verification codes with one click. The whole process is simple and easy to understand, and is very friendly to both developers and users. At the same time, we can also see that the application of jQuery can make our code more concise and easy to understand.

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