A simple GitHub Action written in JavaScript

name: Hello world!
on:
  push:
    branches:
      - main

jobs:
  sayHelloWorld:
    runs-on: ubuntu-latest
    steps:
      - uses: gr2m/hello-world-js-action@v1.x

Customize greeting

name: Hello world!
on:
  push:
    branches:
      - main

jobs:
  sayHelloWorld:
    runs-on: ubuntu-latest
    steps:
      - uses: gr2m/hello-world-js-action@v1.x
        with:
          greeting: Gregor

Recommended reading: The official "Creating a JavaScript action" guide.

gr2m/hello-world-js-action does the following

1. It logs a "Hello, world!" to the output
2. It uses the @actions/core module to showcase how to use dependencies
3. It supports a greeting input
4. It writes the total greeting to outputs
5. It uses @vercel/ncc to compile the code and its dependencies to a single file that can be executed as a standalone GitHub Action.

The most important learning of using Node to create a GitHub Action is that you cannot require/import dependencies. When someone uses your action as part of their workflow, your action's dependencies are not automatically installed. Hence the build step using @vercel/ncc.

Bonus: This action is releasing automatically to GitHub using semantic-release. It also pushes updates to the v1.x branch, which you can reliably depend on in your GitHub workflow (uses: gr2m/hello-world-js-action@v1.x). If there should ever be a breaking release, I'll create a v2.x branch, etc.

ISC