Indicate typescript support in process.features

[silverwind]

What is the problem this feature will solve?

Command line applications that want to load typescript configuration files should be able to detect whether the current node process is able to import typescript files to avoid an error during async import.

What is the feature you are proposing to solve the problem?

Add boolean value process.features.typescript to indicate whether --experimental-strip-types is enabled.

What alternatives have you considered?

It's possible to check for the presence of --experimental-strip-types in either process.execArgv or process.env.NODE_OPTIONS, but doing so is quite cumbersome.

[anonrig]

You can check it by accessing and checking process.argv - https://nodejs.org/docs/latest/api/process.html#processargv

[silverwind]

You can check it by accessing and checking process.argv - https://nodejs.org/docs/latest/api/process.html#processargv

Node-specifc options are not present in argv, only on execArgv. Also, those do not work when NODE_OPTIONS is in use:

$ NODE_OPTIONS="--experimental-strip-types" node -p process.argv
[ '/opt/homebrew/Cellar/node/22.6.0/bin/node' ]

Writing such a check currently would be clumsy and break if the experimental prefix is removed or the option is enabled by default:

const supportsTypescript = (process.env.NODE_OPTIONS ?? "").split(/\s+/).includes("--experimental-strip-types") || process.execArgv.includes("--experimental-strip-types");

[silverwind]

As for my use case of loading a config file, I think I don't strictly need this given that Promise.any can solve this pretty nicely as one could just ignore the import error like this:

async function loadConfig(rootDir: string): Promise<Record<string, any>> {
  let config: Record<string, any> = {};
  try {
    ({default: config} = await Promise.any(["mod.config.ts", "mod.config.js"].map(file => {
      return import(path.join(rootDir, file));
    })));
  } catch {}
  return config;
}

[anonrig]

I think this can still be easily supported on userland with a single line:

const hasTypescript = process.argv.includes("--experimental-strip-types") ?? process.env.NODE_OPTIONS?.includes("--experimental-strip-types")

[silverwind]

I think this can still be easily supported on userland with a single line:

const hasTypescript = process.argv.includes("--experimental-strip-types") ?? process.env.NODE_OPTIONS?.includes("--experimental-strip-types")

This works now, but it's bound to break once the experimental prefix is removed or when the setting is made the default.