Create a JavaScript Action

Use this template to bootstrap the creation of a JavaScript action. 🚀

This template includes compilation support, tests, a validation workflow, publishing, and versioning guidance.

If you are new, there's also a simpler introduction in the Hello world JavaScript action repository.

Create Your Own Action

To create your own action, you can use this repository as a template! Just follow the below instructions:

1. Click the Use this template button at the top of the repository
2. Select Create a new repository
3. Select an owner and name for your new repository
4. Click Create repository
5. Clone your new repository

Important

Make sure to remove or update the CODEOWNERS file! For details on how to use this file, see About code owners.

Initial Setup

After you've cloned the repository to your local machine or codespace, you'll need to perform some initial setup steps before you can develop your action.

Note

You'll need to have a reasonably modern version of Node.js handy. If you are using a version manager like nodenv or nvm, you can run nodenv install in the root of your repository to install the version specified in package.json. Otherwise, 20.x or later should work!

1. 🛠️ Install the dependencies

   npm install

2. 🏗️ Package the JavaScript for distribution

   npm run bundle

3. ✅ Run the tests

   $ npm test
   
   PASS  ./index.test.js
     ✓ throws invalid number (3ms)
     ✓ wait 500 ms (504ms)
     ✓ test runs (95ms)
   
   ...

Update the Action Metadata

The action.yml file defines metadata about your action, such as input(s) and output(s). For details about this file, see Metadata syntax for GitHub Actions.

When you copy this repository, update action.yml with the name, description, inputs, and outputs for your action.

Update the Action Code

The src/ directory is the heart of your action! This contains the source code that will be run when your action is invoked. You can replace the contents of this directory with your own code.

There are a few things to keep in mind when writing your action code:

• Most GitHub Actions toolkit and CI/CD operations are processed asynchronously. In main.js, you will see that the action is run in an async function.

  const core = require('@actions/core')
  //...
  
  async function run() {
    try {
      //...
    } catch (error) {
      core.setFailed(error.message)
    }
  }

  For more information about the GitHub Actions toolkit, see the documentation.

So, what are you waiting for? Go ahead and start customizing your action!

1. Create a new branch

   git checkout -b releases/v1

2. Replace the contents of src/ with your action code

3. Add tests to __tests__/ for your source code

4. Format, test, and build the action

   npm run all

   This step is important! It will run ncc to build the final JavaScript action code with all dependencies included. If you do not run this step, your action will not work correctly when it is used in a workflow. This step also includes the --license option for ncc, which will create a license file for all of the production node modules used in your project.

5. (Optional) Test your action locally

   The @github/local-action utility can be used to test your action locally. It is a simple command-line tool that "stubs" (or simulates) the GitHub Actions Toolkit. This way, you can run your JavaScript action locally without having to commit and push your changes to a repository.

   The local-action utility can be run in the following ways:

   • Visual Studio Code Debugger

     Make sure to review and, if needed, update .vscode/launch.json

   • Terminal/Command Prompt

     # npx local action <action-yaml-path> <entrypoint> <dotenv-file>
     npx local-action . src/main.js .env

   You can provide a .env file to the local-action CLI to set environment variables used by the GitHub Actions Toolkit. For example, setting inputs and event payload data used by your action. For more information, see the example file, .env.example, and the GitHub Actions Documentation.

6. Commit your changes

   git add .
   git commit -m "My first action is ready!"

7. Push them to your repository

   git push -u origin releases/v1

8. Create a pull request and get feedback on your action

9. Merge the pull request into the main branch

Your action is now published! 🚀

For information about versioning your action, see Versioning in the GitHub Actions toolkit.

Validate the Action

You can now validate the action by referencing it in a workflow file. For example, ci.yml demonstrates how to reference an action in the same repository.

steps:
  - name: Checkout
    id: checkout
    uses: actions/checkout@v3

  - name: Test Local Action
    id: test-action
    uses: ./
    with:
      milliseconds: 1000

  - name: Print Output
    id: output
    run: echo "${{ steps.test-action.outputs.time }}"

For example workflow runs, check out the Actions tab! 🚀

Usage

After testing, you can create version tag(s) that developers can use to reference different stable versions of your action. For more information, see Versioning in the GitHub Actions toolkit.

To include the action in a workflow in another repository, you can use the uses syntax with the @ symbol to reference a specific branch, tag, or commit hash.

steps:
  - name: Checkout
    id: checkout
    uses: actions/checkout@v4

  - name: Run my Action
    id: run-action
    uses: actions/javascript-action@v1 # Commit with the `v1` tag
    with:
      milliseconds: 1000

  - name: Print Output
    id: output
    run: echo "${{ steps.run-action.outputs.time }}"