Express is a web application framework for Node.js, designed for building web applications and APIs. It provides a thin layer of fundamental web application features, without obscuring Node.js features that you know and love. Here are some of the core features of the Express framework:
- Routing: Express provides a simple and flexible routing system that allows you to define different routes and actions for different HTTP verbs (GET, POST, PUT, DELETE, etc.). This makes it easy to create APIs that support different HTTP methods.
- Middleware: Express includes a number of built-in middleware functions that are executed before the application’s routes are handled. These middleware functions can be used to perform tasks such as parsing request bodies, adding CORS headers, or implementing authentication.
- Templates: Express supports a number of different templating engines, which are used to render dynamic HTML pages based on data from your application. This makes it easy to build applications that can serve HTML pages with dynamic content.
- Static files: Express can serve static files, such as images, CSS, and JavaScript files. This allows you to easily build applications that serve static assets, in addition to dynamic content.
- Query parameters: Express provides easy-to-use tools for parsing and handling query parameters in URLs. This makes it simple to build APIs that support filtering, pagination, and other common query parameters.
- Error handling: Express provides a built-in error-handling middleware that makes it easy to handle errors in your application. You can define custom error-handling functions to handle specific error types, or use the default error-handling middleware to handle all errors.
In addition to these core features, Express also provides many other useful features, such as support for cookies, sessions, and CORS, as well as a rich ecosystem of third-party plugins and middleware. This makes it a highly flexible and extensible framework for building web applications and APIs with Node.js.