What are common pitfalls when passing data from JavaScript to PHP using POST requests?

One common pitfall when passing data from JavaScript to PHP using POST requests is not properly setting the `Content-Type` header in the JavaScript code. This can result in PHP not being able to correctly interpret the data being sent. To solve this issue, ensure that the `Content-Type` header is set to `application/x-www-form-urlencoded` in the JavaScript code. ```javascript // JavaScript code sending POST request with proper Content-Type header fetch('example.php', { method: 'POST', headers: { 'Content-Type': 'application/x-www-form-urlencoded' }, body: 'data=value' }); ```

// PHP code to receive POST data
$data = $_POST['data'];
echo $data;