Getting started

Prerequisites: JavaScript

Like other modern JavaScript frameworks (for example, Angular 2 and React) LoopBack 4 has an opinion about what flavor of JavaScript to use in your application. The starting point is ECMAScript 6, plus the following non-standard add-ons:

• Decorators
• async / await
• ES2015-modules

All examples and snippets in the documentation use this flavor of JavaScript.

A simple example

Here is the most basic LoopBack 4 application:

import {Application} from '@loopback/core';
import {RestComponent, RestServer} from '@loopback/rest';

const app = new Application({
  components: [RestComponent],
});

(async function start() {
  // Grab the REST server instance
  const server = await app.getServer(RestServer);
  // Setup our handler!
  server.handler((sequence, request, response) => {
    sequence.send(response, 'hello world');
  });
  await app.start();
  console.log(`REST server listening on port ${server.getSync('rest.port')}`);
})();

The example above creates an Application and a RestServer that responds to all HTTP requests with the text “Hello World”.

To see what the complete application looks like, see loopback-next-hello-world.

The following guides introduce the fundamental concepts of LoopBack 4 required to build scalable, maintainable, and consistent APIs.

If you want to try it out locally follow the instructions in Installation.