GitHub Action Script Best Practices

This skill provides guidelines for writing JavaScript files that run using the GitHub Action actions/github-script@v8.

Important Notes

• This action provides @actions/core and @actions/github packages globally
• Do not add import or require for @actions/core
• Reference documentation:
  • https://github.com/actions/toolkit/blob/main/packages/core/README.md
  • https://github.com/actions/toolkit/blob/main/packages/github/README.md

Best Practices

• Use core.info, core.warning, core.error for logging, not console.log or console.error
• Use core.setOutput to set action outputs
• Use core.exportVariable to set environment variables for subsequent steps
• Use core.getInput to get action inputs, with required: true for mandatory inputs
• Use core.setFailed to mark the action as failed with an error message

Step Summary

Use core.summary.* function to write output the step summary file.

• Use core.summary.addRaw() to add raw Markdown content (GitHub Flavored Markdown supported)
• Make sure to call core.summary.write() to flush pending writes
• Summary function calls can be chained, e.g. core.summary.addRaw(...).addRaw(...).write()

Common Errors

• Avoid any type as much as possible, use specific types or unknown instead
• Catch handler: check if error is an instance of Error before accessing message property

catch (error) {
  core.setFailed(error instanceof Error ? error : String(error));
}

• core.setFailed also calls core.error, so do not call both

Typechecking

Run make js to run the typescript compiler.

Run make lint-cjs to lint the files.

Run make fmt-cjs after editing to format the file.