Let's explore these practical examples of creating routes in Express.js in more detail.

🌟 Basic Routes

Let's create a simple Express.js application with routes for different HTTP methods. Each route handles a specific HTTP request and sends a response back to the client.

• GET Route: This route responds to a GET request at the root URL (/). Users who access the application's homepage will receive the message "This is the homepage.";
• POST Route: This route responds to a POST request at the /users URL. It's typically used for creating new user records. The route includes a comment for handling user creation logic, which can be replaced with the actual user creation logic;
• PUT Route: This route responds to a PUT request at the /users/:id URL. It's designed for updating user records based on the :id parameter. Like the POST route, it includes a comment handling user update logic;
• DELETE Route: This route responds to a DELETE request at the /users/:id URL. It's used for deleting user records based on the :id parameter. As with the other routes, it includes a comment for handling user deletion logic.

Note

If you're uncertain about the URL or would like to review the concept, please refer to the following article: URL vs URI vs URN

🌟 Handle URL Parameters

Let's focus on creating a route that handles URL parameters. URL parameters are dynamic parts of a URL that can be used to pass data to the server. Here's how this example works:

• We define a route using app.get('/users/:id', ...), where :id is a URL parameter. This means that when a user accesses a URL like /users/123, the req.params.id variable will contain the value 123;
• Inside the route handler, we access the :id parameter using req.params.id;
• You can replace the comment with logic to fetch user data based on the userId obtained from the URL parameter;
• Finally, we respond to the client with information about the user identified by the :id parameter.

🌟 Route Order and Prioritization

The order in which routes are defined matters because Express uses a first-match-wins strategy. The first matching route will be executed. In this example, we consider a scenario where you have both a specific and a catch-all route:

• The first route, app.get('/users/:id', ...), is a specific route that responds to URLs like /users/123. It will handle requests with a specific user ID;
• The second route, app.get('/users/*', ...), is a catch-all route for generic user-related requests. It uses a wildcard (*) to match any URL that starts with /users/, such as /users/settings.

In this scenario, the order is crucial. The specific route should be defined before the catch-all route to ensure it takes precedence. If you define the catch-all route first, it will match all URLs starting with /users/, and the specific route won't have a chance to handle requests with a user ID.