args-json

Zero-dependency typed command-line argument parser

Installation: npm i args-json

String input

import { parseArgs } from "args-json";

let args = parseArgs("--config=./config.json -v 1.5.12 -d \"lorem ipsum\" -i -n=0 --test-value qwe --debug", {
  v: "version",
  d: "description",
});
// args = {
//   config: "./config.json",
//   version: "1.5.12",
//   description: "lorem ipsum",
//   i: true,
//   n: 0,
//   testValue: "qwe",
//   debug: true,
// };

Note that keys and values can be separated from each other either with a space or an equals sign, and the value can be either quoted or not. These variants are equivalent. Also, keys are converted to camelCase (like --test-value → testValue in the example above).

The second parameter is optional. It is a way to rename argument keys in the output. In the example above, -d and -v in the input string are renamed to description and version in the output object.

Other examples:

let args = parseArgs("--config ./configs/default.json --debug");
// { config: "./configs/default.json", debug: true }

if (args.debug)
  console.log(args.config);

The first line is also equivalent to:

let args = parseArgs("--config \"./configs/default.json\" --debug");

or

let args = parseArgs("--config=./configs/default.json --debug");

or

let args = parseArgs("--config=\"./configs/default.json\" --debug");

String array input

let args = parseArgs(["--config", "./configs/default.json", "--debug"]);
// { config: "./configs/default.json", debug: true }

if (args.debug)
  console.log(args.config);

Node process arguments

In a Node environment, parseArgs() without parameters parses the node process arguments.

let args = parseArgs();

is equivalent to

let args = parseArgs(process.argv);

Key mapping

let args = parseArgs("-c ./configs/default.json --debug", { c: "config" });
// { config: "./configs/default.json", debug: true }

if (args.debug)
  console.log(args.config);

As specified with the second parameter of parseArgs(), -c is mapped to config in the output.

Value parsing

Values are JSON.parsed if they are parsable.

let args = parseArgs("-d \"{\"x\":10}\" -i 0 -n=3 -c ./config.json");
// { d: { x: 10 }, i: 0, n: 3, c: "./config.json" }

Typing

The output type can be specified by providing a generic type to parseArgs<T>().

type CustomShape = {
  level?: number;
  debug?: boolean;
};

let args = parseArgs<CustomShape>("--level=0 --debug");

if (args.debug)
  console.log(`Level: ${args.level}`);