How to prevent form resubmission on page refresh in HTML?
Jul 14, 2025 am 02:12 AM
Refreshing after submitting a form may lead to repeated submissions, which can be avoided in three ways: 1. Using PRG mode, the server returns a redirect response after processing the POST request, causing the user to jump to a new page to prevent repeated submissions; 2. The front-end uses JavaScript to disable the submission button after the first submission or prevent repeated triggers, which is suitable for simple scenarios; 3. Using Session Token, embed a one-time token in the form, verify and invalidate it during submission, which is suitable for highly concurrent or sensitive operations.
When you submit a form on a web page, if the refresh page submits the same content again, it may cause duplicate data or unexpected operations. This problem is common, but there are several practical ways to avoid it.
Use Post/Redirect/Get (PRG) mode
This is the most common and recommended method. After the user submits the form, the server returns a redirect response (usually 303 or 302) after processing the POST request, and the browser will jump to the new URL instead of staying on the original submission page.
For example:
- Users visit
form.htmlto submit data - The backend receives a POST request and returns
Location: success.htmlafter processing the data. - The browser will automatically jump to
success.html
This way, even if the user refreshes the page, it will just reload success.html without repeatedly submitting the form.
The key points to achieve are:
- The backend must correctly set the HTTP status code and Location header
- The form page and the processing page should be designed separately
Use JavaScript on the front end to prevent duplicate submissions
If you don't want to or can't use backend redirection, you can use JavaScript to control whether the form allows resubmission.
A common practice is to disable the submit button after the user's first submission:
<form onsubmit="this.submitButton.disabled = true;"> <!-- Form content--> <button type="submit" name="submitButton">Submit</button> </form>
Or be more flexible and make judgments in JS:
<script>
let submitted = false;
document.querySelector('form').addEventListener('submit', function(e) {
if (submitted) {
e.preventDefault();
} else {
submitted = true;
}
});
</script>This approach is suitable for simple scenarios, but it does not completely prevent users from repeating submissions through manual refresh of the address bar.
Leverage Session Token (one-time token)
This method is more suitable for preventing malicious forms swiping or repeated submission problems under high concurrency. The basic idea is: generate a unique token when loading the form and save it in the session; verify whether the token is valid when submitting, and the token will be invalidated immediately after the verification is successful.
The steps are as follows:
- Generate a random token when the page is loaded and embedded in the form hidden field
- When the user submits, the server checks whether the token matches and has not been used.
- If it matches, process the request and mark the token used
- The token is illegal when submitting again, and the execution is refused
This method is relatively safe, but requires front-end cooperation and is suitable for sensitive operations such as order submission, payment, etc.
Conclusion
These methods have their own applicable scenarios: the PRG mode is simple and effective, the JS method is convenient and fast, and the token is safer but has a slightly more complexity. Just choose the right method according to your project needs. Basically that's it.
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