Developing the Frontend UI¶

This guide explains how to run the Browsertrix frontend development server with Yarn.

Instead of rebuilding the entire frontend image to view your UI changes, you can use the included local development server to access the frontend from your browser. This setup is ideal for rapid UI development that does not rely on any backend changes.

Requirements¶

1. Browsertrix API backend already in a Kubernetes cluster¶

The frontend development server requires an existing backend that has been deployed locally or is in production. See Deploying Browsertrix.

2. Node.js ≥18 and Yarn 1¶

To check if you already have Node.js installed, run the following command in your command line terminal:

node --version

You should see a version number like v18.12.1. If you see a command line error instead of a version number, install Node.js before continuing.

What if my other project requires a different version of Node.js?

You can use Node Version Manager to install multiple Node.js versions and switch versions between projects.

To check your Yarn installation:

yarn --version

You should see a version number like 1.22.19. If you do not, install or upgrade Yarn.

Quickstart¶

From the command line, change your current working directory to /frontend:

cd frontend

Note

From this point on, all commands in this guide should be run from the frontend directory.

Install UI dependencies:

yarn install

Copy environment variables from the sample file:

cp sample.env.local .env.local

Update API_BASE_URL in .env.local to point to your backend API host. For example:

API_BASE_URL=http://dev.example.com

Note

This setup assumes that your API endpoints are available under /api, which is the default configuration for the Browsertrix backend.

If connecting to a local deployment cluster, set API_BASE_URL to:

API_BASE_URL=http://localhost:30870

Port when using Minikube (on macOS)

When using Minikube on macOS, the port will not be 30870. Instead, Minikube opens a tunnel to a random port, obtained by running minikube service browsertrix-cloud-frontend --url in a separate terminal.

Set API_BASE_URL to provided URL instead, eg. API_BASE_URL=http://127.0.0.1:<TUNNEL_PORT>

Start the frontend development server:

yarn start

This will open localhost:9870 in a new tab in your default browser.

Saving changes to files in src will automatically reload your browser window with the latest UI updates.

To stop the development server type Ctrl+C into your command line terminal.

Scripts¶

`yarn <name>`
`start`	runs app in development server, reloading on file changes
`test`	runs tests in chromium with playwright
`build-dev`	bundles app and outputs it in `dist` directory
`build`	bundles app, optimized for production, and outputs it to `dist`
`lint`	find and fix auto-fixable javascript errors
`format`	formats js, html, and css files
`localize:extract`	generate XLIFF file to be translated
`localize:build`	output a localized version of strings/templates

Testing¶

Tests assertions are written in Chai.

To watch for file changes while running tests:

yarn test --watch

To run tests in multiple browsers:

yarn test --browsers chromium firefox webkit

Localization¶

Wrap text or templates in the msg helper to make them localizable:

// import from @lit/localize:
import { msg } from "@lit/localize";

// later, in the render function:
render() {
  return html`
    <button>
      ${msg("Click me")}
    </button>
  `
}

Entire templates can be wrapped as well:

render() {
  return msg(html`
    <p>Click the button</p>
    <button>Click me</button>
  `)
}

See: https://lit.dev/docs/localization/overview/#message-types

To add new languages:

Add BCP 47 language tag to targetLocales in lit-localize.json
Run yarn localize:extract to generate new .xlf file in /xliff
Provide .xlf file to translation team
Replace .xlf file once translated
Run yarn localize:build bring translation into src

See: https://lit.dev/docs/localization/overview/#extracting-messages