@carnesen/run-and-exit

Run a function or async function, console.log the result, and process.exit

Install

$ npm install @carnesen/run-and-exit

This package includes runtime JavaScript files (ES2015 + CommonJS) as well as the corresponding TypeScript type declarations.

Usage

Here's a JavaScript example with an async function that fails:

// example.js
const { runAndExit } = require('@carnesen/run-and-exit');
const { readFile } = require('fs');
const { promisify } = require('util');

runAndExit(async () => {
  const fileContents = await promisify(readFile)('/foo/bar/baz', 'utf8');
  return fileContents;
});

$ node example.js
{ Error: ENOENT: no such file or directory, open '/foo/bar/baz'
  errno: -2,
  code: 'ENOENT',
  syscall: 'open',
  path: '/foo/bar/baz' }
$ echo $?
1

Here's a TypeScript example with a synchronous function that succeeds:

// example.ts
import { runAndExit } from '@carnesen/run-and-exit';

const concat = (a: string, b: string) => `${a}-${b}`;
runAndExit(concat, 'foo', 'bar');

$ ts-node example.ts
foo-bar
$ echo $?
0

runAndExit is intelligently typed in the sense that, continuing the previous example, the TypeScript compiler would complain if you tried this:

// NOT OK
runAndExit(concat, 'foo', 3);
// ^^ error TS2345: Argument of type '3' is not assignable to parameter of type 'string'.

This is achieved using "rest parameters with tuple types", new in TypeScript 3.0. If you're using an older version of TypeScript, runAndExit may not work as advertised here.

API

runAndExit(fn, ...args)

Runs the provided function fn with arguments args.

fn

A function. Can return/throw a value synchronously or return a Promise (e.g. an async function). If fn throws or returns a promise that rejects, the exception is console.logged and then process.exit(1) is called. In particular this means that if you don't want a show a stack trace in the terminal, fn should throw a string instead of an Error object. If fn returns a non-Promise value or a Promise that resolves, the value is console.logged and then process.exit(0) is called.

args

Arguments passed to fn. If using TypeScript, args must be assignable to the parameter types of fn just as if you were calling fn(args) directly.

More information

This micro-package has a half dozen unit tests with 100% coverage. If you want to see more examples of how it works, those tests would be a good place to start. If you encounter any bugs or have any questions or feature requests, please don't hesitate to file an issue or submit a pull request on this project's repository on GitHub.

Related

• @carnesen/cli: A library for building Node.js command-line interfaces

License

MIT © Chris Arnesen