Building RESTful APIs with Express

• REST defines a set of conventions for creating HTTP services:
• POST: to create a resource
• PUT: to update it
• GET: to read it
• DELETE: to delete it
• Express is a simple, minimalistic and lightweight framework for building web servers.

Additional

• We use Nodemon to watch for changes in files and automatically restart the node process.
• We can use environment variables to store various settings for an application. To read an environment variable, we use process.env.

// Reading the port from an environment variable
const port = process.env.PORT || 3000;
app.listen(port);

• Always validate! Use Joi package to perform input validation.

Express: Advanced

• A middleware function is a function that takes a request object and either terminates the request/response cycle or passes control to another middleware function.
• Express has a few built-in middleware functions:
• json(): to parse the body of requests with a JSON payload
• urlencoded(): to parse the body of requests with URL-encoded payload
• static(): to serve static files
• You can create custom middleware for cross-cutting concerns, such as logging, authentication, etc.

// Custom middleware (applied on all routes)
app.use(function(req, res, next)) {
 // …
 next();
}
// Custom middleware (applied on routes starting with /api/admin)
app.use(‘/api/admin’, function(req, res, next)) {
 // …
 next();
}

• We can detect the environment in which our Node application is running (development, production, etc) using process.env.NODE_ENV and app.get(‘env’).
• The config package gives us an elegant way to store configuration settings for our applications.
• We can use the debug package to add debugging information to an application. Prefer this approach to console.log() statements.
• To return HTML markup to the client, use a templating engine. There are various templating engines available out there. Pug, EJS and Mustache are the most popular ones.