Javascript implementation of verification code refresh ie is invalid

With the development of the Internet, verification codes (Captcha) have become more and more common. By asking users to enter difficult-to-read text, images, and audio, CAPTCHAs prevent automated malware attacks on websites and fraud.

However, in the process of implementing verification codes, a common problem is that verification code refresh is often invalid in Internet Explorer (IE). If you're also experiencing this issue, below we'll go over some possible causes and how to fix it.

Why does the verification code refresh not work in IE?

1. IE cache problem: IE cache can save page loading time, but it may also cause the verification code to be invalid.
2. JavaScript issues in IE: IE's JavaScript engine is different from other modern browsers, which may cause the verification code to be invalid.
3. Security settings in IE: The security settings of IE may restrict certain JavaScript functions, causing the verification code to be invalid.

Solution

1. Disable IE cache

Disabling IE browser cache is probably one of the easiest ways to solve this problem. You can add the following to your code to ensure that IE does not cache the verification code image:

<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="0" />

This will tell IE not to cache anything, so the verification code image will be cached on every refresh Reload. Please note that this approach may affect your site's performance.

2. Use different JavaScript code

Since IE’s JavaScript engine is different from other modern browsers, you can try to use different JavaScript code to solve the problem of invalid verification code . Here is a possible solution:

document.getElementById("captcha").src = "captcha.php?" + Math.random();

In this code, we use a simple Math.random() function to generate a random number that is called every time the verification code is refreshed. This will cause IE to not cache the captcha image and reload it on every refresh.

3. Change IE security settings

If IE's security settings restrict certain JavaScript functions, you can try changing these settings. Here are some steps you can try:

• Make sure JavaScript is enabled in IE.
• Add the website to IE's trusted sites list. In this list, you can change the security level and allow all JavaScript features.
• Disable IE's protected mode. You can find Protected Mode in IE's Internet Options and disable it.

Summary

The above are some possible solutions to help you solve the problem of invalid verification code refresh in IE browser. However, today's browser market share is far beyond IE, and using more modern browsers (such as Chrome, Firefox, Edge, etc.) may be a better choice.

Whatever your choice, you should always remember that implementing CAPTCHA is one of the key steps in protecting your website from malicious attacks.

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