Are there any specific tools or techniques recommended for safely testing website changes before making them live?

When making changes to a website, it is important to test them thoroughly before making them live to ensure they do not cause any issues or errors. One recommended technique is to create a staging environment where you can safely test changes without affecting the live site. This can be done by duplicating the website on a separate server or subdomain. Additionally, using tools like browser developer tools, website testing services, and version control systems can help identify and fix any issues before deploying changes to the live site.

// Example PHP code for creating a staging environment

// Define the staging domain
define('STAGING_DOMAIN', 'staging.example.com');

// Check if the current domain is the staging domain
if($_SERVER['HTTP_HOST'] === STAGING_DOMAIN){
    // Connect to the staging database
    $db_host = 'staging_db_host';
    $db_user = 'staging_db_user';
    $db_pass = 'staging_db_pass';
    $db_name = 'staging_db_name';
    $conn = new mysqli($db_host, $db_user, $db_pass, $db_name);
    
    // Perform testing and changes on the staging environment
    // Once changes are verified, deploy them to the live site
}