@carnesen/run-and-exit
v1.0.0
Published
Run a function or async function, console.log the result, and exit
Downloads
1,377
Readme
@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.log
ged 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.log
ged 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