What best practices should be followed when using AJAX to handle form submissions in PHP?

When using AJAX to handle form submissions in PHP, it is important to sanitize and validate user input to prevent SQL injection and other security vulnerabilities. Additionally, make sure to properly handle errors and provide meaningful feedback to the user. Finally, consider implementing CSRF protection to prevent cross-site request forgery attacks. 

<?php

// Sanitize and validate user input
$input_data = filter_input_array(INPUT_POST, [
    'input_field' => FILTER_SANITIZE_STRING,
]);

// Handle form submission
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // Process the form data
    // Validate input data
    // Perform necessary actions
    // Return success or error message
}

// CSRF protection
$token = bin2hex(random_bytes(32));
$_SESSION['csrf_token'] = $token;

?>

<!-- HTML form with AJAX submission -->
<form id="myForm">
    <input type="text" name="input_field" id="input_field">
    <input type="hidden" name="csrf_token" value="<?php echo $token; ?>">
    <button type="submit" id="submit_btn">Submit</button>
</form>

<script>
    document.getElementById('myForm').addEventListener('submit', function(e) {
        e.preventDefault();
        
        var formData = new FormData(this);
        
        fetch('process_form.php', {
            method: 'POST',
            body: formData
        })
        .then(response => response.json())
        .then(data => {
            // Handle success or error response
        })
        .catch(error => console.error('Error:', error));
    });
</script>

Keywords

AJAX form submissions PHP security validation

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