How can PHP prevent a script from being executed again when a user clicks "back" or "reload" in the browser?

When a user clicks "back" or "reload" in the browser, a script may be executed again, leading to potential duplicate actions or undesired outcomes. To prevent this, we can use a technique called "POST/Redirect/GET" (PRG) pattern in PHP. This involves redirecting the user to a different URL after processing a form submission, effectively preventing the script from being executed again upon refreshing the page. 

// Check if form has been submitted
if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    // Process form data
    
    // Redirect to a different URL to prevent script execution on refresh
    header("Location: success.php");
    exit;
}

Keywords

session token form submission POST method header redirect

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