Creating a JavaScript action

In this tutorial, you'll learn how to build a JavaScript action using the actions toolkit.

本文内容

Introduction

In this guide, you'll learn about the basic components needed to create and use a packaged JavaScript action. To focus this guide on the components needed to package the action, the functionality of the action's code is minimal. The action prints "Hello World" in the logs or "Hello [who-to-greet]" if you provide a custom name.

This guide uses the GitHub Actions Toolkit Node.js module to speed up development. For more information, see the actions/toolkit repository.

Once you complete this project, you should understand how to build your own JavaScript action and test it in a workflow.

要确保您的 JavaScript 操作与所有 GitHub 托管的运行器（Ubuntu、Windows 和 macOS）兼容，您编写的封装 JavaScript 代码应该是纯粹的 JavaScript，不能依赖于其他二进制文件。 JavaScript 操作直接在运行器上运行，并使用运行器映像中已存在的二进制文件。

警告

创建工作流和操作时，应始终考虑代码是否可能执行潜在攻击者的不受信任的输入。 某些上下文应被视为不受信任的输入，因为攻击者可能会插入自己的恶意内容。 有关详细信息，请参阅“GitHub Actions 的安全强化”。

Prerequisites

Before you begin, you'll need to download Node.js and create a public GitHub repository.

  1. Download and install Node.js 20.x, which includes npm.

    https://nodejs.org/en/download/

  2. Create a new public repository on GitHub and call it "hello-world-javascript-action". For more information, see 创建新仓库.

  3. Clone your repository to your computer. For more information, see 克隆仓库.

  4. From your terminal, change directories into your new repository.

    Shell
    cd hello-world-javascript-action

  5. From your terminal, initialize the directory with npm to generate a package.json file.

    Shell
    npm init -y

Creating an action metadata file

Create a new file named action.yml in the hello-world-javascript-action directory with the following example code. For more information, see GitHub Actions 的元数据语法.

YAML
name: Hello World
description: Greet someone and record the time

inputs:
  who-to-greet: # id of input
    description: Who to greet
    required: true
    default: World

outputs:
  time: # id of output
    description: The time we greeted you

runs:
  using: node20
  main: dist/index.js

This file defines the who-to-greet input and time output. It also tells the action runner how to start running this JavaScript action.

Adding actions toolkit packages

The actions toolkit is a collection of Node.js packages that allow you to quickly build JavaScript actions with more consistency.

The toolkit @actions/core package provides an interface to the workflow commands, input and output variables, exit statuses, and debug messages.

The toolkit also offers a @actions/github package that returns an authenticated Octokit REST client and access to GitHub Actions contexts.

The toolkit offers more than the core and github packages. For more information, see the actions/toolkit repository.

At your terminal, install the actions toolkit core and github packages.

Shell
npm install @actions/core @actions/github

You should now see a node_modules directory and a package-lock.json file which track any installed dependencies and their versions. You should not commit the node_modules directory to your repository.

Writing the action code

This action uses the toolkit to get the who-to-greet input variable required in the action's metadata file and prints "Hello [who-to-greet]" in a debug message in the log. Next, the script gets the current time and sets it as an output variable that actions running later in a job can use.

GitHub Actions provide context information about the webhook event, Git refs, workflow, action, and the person who triggered the workflow. To access the context information, you can use the github package. The action you'll write will print the webhook event payload to the log.

Add a new file called src/index.js, with the following code.

JavaScript
import * as core from "@actions/core";
import * as github from "@actions/github";

try {
  // `who-to-greet` input defined in action metadata file
  const nameToGreet = core.getInput("who-to-greet");
  core.info(`Hello ${nameToGreet}!`);

  // Get the current time and set it as an output variable
  const time = new Date().toTimeString();
  core.setOutput("time", time);

  // Get the JSON webhook payload for the event that triggered the workflow
  const payload = JSON.stringify(github.context.payload, undefined, 2);
  core.info(`The event payload: ${payload}`);
} catch (error) {
  core.setFailed(error.message);
}

If an error is thrown in the above index.js example, core.setFailed(error.message); uses the actions toolkit @actions/core package to log a message and set a failing exit code. For more information, see 设置操作的退出代码.

Creating a README

To let people know how to use your action, you can create a README file. A README is most helpful when you plan to share your action publicly, but is also a great way to remind you or your team how to use the action.

In your hello-world-javascript-action directory, create a README.md file that specifies the following information:

  • A detailed description of what the action does.
  • Required input and output arguments.
  • Optional input and output arguments.
  • Secrets the action uses.
  • Environment variables the action uses.
  • An example of how to use your action in a workflow.
Markdown
# Hello world JavaScript action

This action prints "Hello World" or "Hello" + the name of a person to greet to the log.

## Inputs

### `who-to-greet`

**Required** The name of the person to greet. Default `"World"`.

## Outputs

### `time`

The time we greeted you.

## Example usage

```yaml
uses: actions/hello-world-javascript-action@e76147da8e5c81eaf017dede5645551d4b94427b
with:
  who-to-greet: Mona the Octocat
```

Commit, tag, and push your action

GitHub downloads each action run in a workflow during runtime and executes it as a complete package of code before you can use workflow commands like run to interact with the runner machine. This means you must include any package dependencies required to run the JavaScript code. For example, this action uses @actions/core and @actions/github packages.

Checking in your node_modules directory can cause problems. As an alternative, you can use tools such as rollup.js or @vercel/ncc to combine your code and dependencies into one file for distribution.

  1. Install rollup and its plugins by running this command in your terminal.

    npm install --save-dev rollup @rollup/plugin-commonjs @rollup/plugin-node-resolve

  2. Create a new file called rollup.config.js in the root of your repository with the following code.

    JavaScript
    import commonjs from "@rollup/plugin-commonjs";
import { nodeResolve } from "@rollup/plugin-node-resolve";

const config = {
  input: "src/index.js",
  output: {
    esModule: true,
    file: "dist/index.js",
    format: "es",
    sourcemap: true,
  },
  plugins: [commonjs(), nodeResolve({ preferBuiltins: true })],
};

export default config;

  3. Compile your dist/index.js file.

    rollup --config rollup.config.js

    You'll see a new dist/index.js file with your code and any dependencies.

  4. From your terminal, commit the updates.

    Shell
    git add src/index.js dist/index.js rollup.config.js package.json package-lock.json README.md action.yml
git commit -m "Initial commit of my first action"
git tag -a -m "My first action release" v1.1
git push --follow-tags

When you commit and push your code, your updated repository should look like this:

hello-world-javascript-action/
├── action.yml
├── dist/
│   └── index.js
├── package.json
├── package-lock.json
├── README.md
├── rollup.config.js
└── src/
    └── index.js

Testing out your action in a workflow

Now you're ready to test your action out in a workflow.

Public actions can be used by workflows in any repository. When an action is in a private repository, the repository settings dictate whether the action is available only within the same repository or also to other repositories owned by the same user or organization. For more information, see 管理存储库的 GitHub Actions 设置.

Example using a public action

This example demonstrates how your new public action can be run from within an external repository.

Copy the following YAML into a new file at .github/workflows/main.yml, and update the uses: octocat/hello-world-javascript-action@1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b line with your username and the name of the public repository you created above. You can also replace the who-to-greet input with your name.

YAML
on:
  push:
    branches:
      - main

jobs:
  hello_world_job:
    name: A job to say hello
    runs-on: ubuntu-latest

    steps:
      - name: Hello world action step
        id: hello
        uses: octocat/hello-world-javascript-action@1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b
        with:
          who-to-greet: Mona the Octocat

      # Use the output from the `hello` step
      - name: Get the output time
        run: echo "The time was ${{ steps.hello.outputs.time }}"

When this workflow is triggered, the runner will download the hello-world-javascript-action action from your public repository and then execute it.

Example using a private action

Copy the workflow code into a .github/workflows/main.yml file in your action's repository. You can also replace the who-to-greet input with your name.

YAML
on:
  push:
    branches:
      - main

jobs:
  hello_world_job:
    name: A job to say hello
    runs-on: ubuntu-latest

    steps:
      # To use this repository's private action,
      # you must check out the repository
      - name: Checkout
        uses: actions/checkout@v4

      - name: Hello world action step
        uses: ./ # Uses an action in the root directory
        id: hello
        with:
          who-to-greet: Mona the Octocat

      # Use the output from the `hello` step
      - name: Get the output time
        run: echo "The time was ${{ steps.hello.outputs.time }}"

从存储库中，单击“操作”选项卡，然后选择最新的工作流运行。 在“作业”下或可视化图中，单击“表示问候的作业” 。

单击“Hello world action step”，应该会看到“Hello Mona the Octocat”或日志中输出的用于 who-to-greet 输入的名称。 要查看时间戳，单击“获取输出时间”。

Template repositories for creating JavaScript actions

GitHub provides template repositories for creating JavaScript and TypeScript actions. You can use these templates to quickly get started with creating a new action that includes tests, linting, and other recommended practices.

Example JavaScript actions on GitHub.com

You can find many examples of JavaScript actions on GitHub.com.