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One of the basic requirements of a web app is the ability to serve static files. Serving static files from a LoopBack application is very simple - just call the app.static(urlPath, rootDir[, options]) method. The variables in the API are explained below.

  • app: An instance of a LoopBack application.
  • urlPath: The path where the static assets are to be served from. Refer to path examples in the Express docs for possible values.
  • rootDir: The directory where the static assets are located on the file system.
  • options: An optional object for configuring the underlying express.static middleware.

Here is an example of configuring an app to serve the static assets from a directory named public at /.

src/application.ts

import * as path from 'path';

export class TodoListApplication extends BootMixin(
  ServiceMixin(RepositoryMixin(RestApplication)),
) {
  constructor(options: ApplicationConfig = {}) {
    super(options);

    // ...

    this.static('/', path.join(__dirname, '../../public'));
  }
}

You can call app.static() multiple times to configure the app to serve static assets from different drectories.

app.static('/files', path.join(__dirname, 'files'));
app.static('/downloads', path.join(__dirname, 'mp3s'));

You can also call app.static() multiple times on the same mounth path to merge files from multiple filesystem directories and expose them on the same URL path. When a file with the same name is present in multiple directories mounted at the same URL path, then the precedence is given the file from the directory that was registered earlier.

app.static('/files', path.join(__dirname, 'files'));
app.static('/files', path.join(__dirname, 'other-files'));

And app.static() can be called even after the app have started.

await app.boot();
await app.start();
app.static('/files', path.join(__dirname, 'files'));