Use NodeJS v16 as runtime for JavaScript actions

This month GitHub supported NodeJS v16 as runtime for JavaScript actions. It is also supported by GitHub Enterprise Servers (GHES) 3.0 and later.

Motivation to use NodeJS v16

How to update the project

We can complete the minimal migration by updating run.using in the actions.yml file. We may need several additional updates like below:

Update engines.node in package.json

If you have specified the version of NodeJS to use in package.json, you will need to update it.
16.13.1 is the current latest version, so the preferred configuration would be as follows:

"engines": {
    "node": "^16.13.1"
  }

Update tsconfig.json

NodeJS v16 lets us use ES2021. Based on the official TSConfig settings recommendation for NodeJS v16, update the compilerOptions as follows:

"compilerOptions": {
    "lib": ["ES2021"],
    "module": "commonjs",
    "target": "ES2021"
  }

Update TypeScript

If your TypeScript is too old to use ES2021, it is suggested to update.

Note that TypeScript v4.4 changed the type of caught error from any to unknown by default.
So if your action catches error to invoke core.setFailed() method, you need to check the type of caught object in runtime:

-     core.setFailed(error)
+     if (error instanceof Error) {
+       core.setFailed(error)
+     } else {
+       core.setFailed(JSON.stringify(error))
+     }

Update ESLint

If you've updated your TypeScript, it is necessary to update ESLint too. If you've created projects based on the official template project, you can run the following command to upgrade ESLint and its plugins in batch:

$ npm add -D eslint@^8.5.0 @typescript-eslint/parser@^5.8.0 eslint-plugin-github@^4.3.5 eslint-plugin-jest@^25.3.0

If you found lint failure caused by changes on the ESLint side, copy the default .eslintrc.json from the template project, or follow ESLint's migration guide documented in its GitHub Releases.

Update GitHub Actions Workflow to use NodeJS v16

If you use the default NodeJS on the PATH, you need no action because GitHub hosted runners use NodeJS v16 by default since this Dec/10th.

If you use actions/setup-node to specify the version of NodeJS, you need to update the node-version config in the workflow definitions.

Or if you have a configuration file like .node-version and .nvmrc, you can use the node-version-file config supported from v2.5.0.

Wrap up

NodeJS v12 will reach its end-of-life soon. All system running on NodeJS needs to be migrated, and GitHub JavaScript Actions are also in the target.

The migration process is quite simple, just update metadata and run the build with NodeJS v16. You may refer to my PR for gradle/wrapper-validation-action as example. Enjoy!