Add a New Lit Project

The code for this example is available on Github:

{% github-repository url="https://github.com/nrwl/nx-recipes/tree/main/lit" /%}

Supported Features

Because we are not using an Nx plugin for Lit, there are few items we'll have to configure manually. We'll have to configure our own build system. There are no pre-created Lit-specific code generators. And we'll have to take care of updating any framework dependencies as needed.

{% pill url="/core-features/run-tasks" %}✅ Run Tasks{% /pill %} {% pill url="/core-features/cache-task-results" %}✅ Cache Task Results{% /pill %} {% pill url="/core-features/remote-cache" %}✅ Share Your Cache{% /pill %} {% pill url="/core-features/explore-graph" %}✅ Explore the Graph{% /pill %} {% pill url="/core-features/distribute-task-execution" %}✅ Distribute Task Execution{% /pill %} {% pill url="/core-features/integrate-with-editors" %}✅ Integrate with Editors{% /pill %} {% pill url="/core-features/automate-updating-dependencies" %}✅ Automate Updating Nx{% /pill %} {% pill url="/core-features/enforce-module-boundaries" %}✅ Enforce Module Boundaries{% /pill %} {% pill url="/core-features/plugin-features/use-task-executors" %}🚫 Use Task Executors{% /pill %} {% pill url="/core-features/plugin-features/use-code-generators" %}🚫 Use Code Generators{% /pill %} {% pill url="/core-features/automate-updating-dependencies" %}🚫 Automate Updating Framework Dependencies{% /pill %}

Install Lit and Other Dependencies

Install all the dependencies we need:

{% tabs %} {%tab label="npm"%}

npm i --save-dev @nx/node lit http-server

{% /tab %} {%tab label="yarn"%}

yarn add --dev @nx/node lit http-server

{% /tab %} {% /tabs %}

Create an Application

{% callout type="note" title="Directory Flag Behavior Changes" %} The command below uses the as-provided directory flag behavior, which is the default in Nx 16.8.0. If you're on an earlier version of Nx or using the derived option, omit the --directory flag. See the workspace layout documentation for more details. {% /callout %}

We'll start with a node application and then tweak the settings to match what we need. Add a new node application to your workspace with the following command:

nx g @nx/node:app my-lit-app --directory=apps/my-lit-app

Choose none for the node framework, since we won't be using this as a node app.

Turn the Application into a Lit Application

Update main.ts:

import { LitElement, html } from 'lit';
import { customElement, property } from 'lit/decorators.js';

@customElement('my-element')
export class MyElement extends LitElement {
  @property()
  version = 'STARTING';

  render() {
    return html`
      <p>Welcome to the Lit tutorial!</p>
      <p>This is the ${this.version} code.</p>
    `;
  }
}

Create index.html:

<!DOCTYPE html>
<html>
  <head>
    <script type="module" src="main.js"></script>
    <style>
      body {
        font-family: 'Open Sans', sans-serif;
        font-size: 1.5em;
        padding-left: 0.5em;
      }
    </style>
  </head>
  <body>
    <my-element></my-element>
  </body>
</html>

Update the Build Task

In the project.json file update the options under the build target. The properties that need to change are format, bundle, thirdParty, and assets:

{
  "targets": {
    "build": {
      "executor": "@nx/esbuild:esbuild",
      "outputs": ["{options.outputPath}"],
      "defaultConfiguration": "production",
      "options": {
        "outputPath": "dist/apps/my-lit-app",
        "format": ["esm"],
        "bundle": true,
        "thirdParty": true,
        "main": "apps/my-lit-app/src/main.ts",
        "tsConfig": "apps/my-lit-app/tsconfig.app.json",
        "assets": ["apps/my-lit-app/src/assets", "apps/my-lit-app/index.html"],
        "generatePackageJson": true,
        "esbuildOptions": {
          "sourcemap": true,
          "outExtension": {
            ".js": ".js"
          }
        }
      }
    }
  }
}

Now, when you run the build, there should be index.html, main.js and package.json under dist/apps/my-lit-app. Try it out:

nx build my-lit-app

Update the Serve Task

To serve the app, we'll completely overwrite the existing serve task. Change it to this:

{
  "targets": {
    "serve": {
      "dependsOn": ["build"],
      "executor": "nx:run-commands",
      "options": {
        "commands": [
          "http-server dist/apps/my-lit-app",
          "nx watch --projects=my-lit-app --includeDependentProjects -- nx build my-lit-app"
        ]
      }
    }
  }
}

"dependsOn": ["build"] will ensure that the build task is always run before the serve task. The entries under commands will each be run in parallel. The http-server line serves the build output with a simple server. The nx watch line will automatically re-run the build task any time the application code or any project it depends on changes.

Run the serve task and see your Lit app in action:

nx serve my-lit-app

Create a Library

Let's create a library that our Lit application is going to consume. To create a new library, install the @nx/js package and run:

nx g @nx/js:lib my-lib --directory=libs/my-lib

Once the library is created, update the following files.

export function someFunction(): string {
  return 'some function';
}

import { LitElement, html } from 'lit';
import { customElement, property } from 'lit/decorators.js';
import { someFunction } from '@my-org/my-lib';

@customElement('my-element')
export class MyElement extends LitElement {
  @property()
  version = 'STARTING';

  render() {
    return html`
      <p>Welcome to the Lit tutorial!</p>
      <p>This is the ${this.version} code.</p>
      <p>Imported from a library: ${someFunction()}.</p>
    `;
  }
}

Now when you serve your application, you'll see the content from the library being displayed.

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