larser

A Minimal and lightweight, 0 dependency package for parsing command line arguments that's only a few bytes.

Basic Usage

The following is a basic example of using larser:

import larser from "larser";

// Or for CJS

let larser;

import("larser").then((module) => {
  larser = module;
});

const argv = process.argv;
const parsed = larser(argv);

console.log(parsed);

/**
 * --testI=1233 --testII=3112
 *
 * Expected Output:
 *
 * { _: [], testI: '1233', testII: '3112' }
 */

Aliases

Using aliases is also supported by larser:

import larser from "larser";

const argv = process.argv;
const parsed = larser(argv, {
  aliases: {
    testI: ["t1", "te1"],
    testII: ["t2", "te2"],
  },
});

console.log(parsed);

/**
 * --t1=1233 --t2=3112
 *
 * Expected Output:
 *
 * {
 *  _: [],
 *  testI: '1233',
 *  t1: '1233',
 *  te1: '1233',
 *  testII: '3112',
 *  t2: '3112',
 *  te2: '3112'
 * }
 */

Default

You can also set defaults when the user does not provide a value:

import larser from "larser";

const argv = process.argv;
const parsed = larser(argv, {
  default: {
    t: "default",
    b: "default",
  },
});

console.log(parsed);

/**
 * --b=notdefault
 *
 * Expected Output:
 *
 * {
 *  _: [],
 *  t: "default",
 *  b: "notdefault"
 * }
 */

CJS Usage

Though we do recommend using ESM, you can also import this module using import() that is available in most CJS setups.

And then you can use it just as normal.

Argument Types

--X=Y

Having a double dash will result in a key-value pair separated by =.

This should return, once parsed:

X: Y

-XYZ

Having a single dash will result in a key-value pair with it's value being true.

This should return, once parsed:

X: true,
Y: true,
Z: true

X YZ ZY

Having no dashes will result in the string being pushed into the root variable _.

This should return once parsed:

_: ["X", "YZ", "ZY"]

Benchmarks

Benchmark with 40 arguments:
minimist      x 11,799 ops/sec ±1.35% (88 runs sampled)
larser        x 37,481 ops/sec ±1.67% (87 runs sampled)
mri           x 46,089 ops/sec ±0.80% (93 runs sampled)
nopt          x 113,870 ops/sec ±1.94% (89 runs sampled)
yargs-parser  x 1,092 ops/sec ±6.00% (76 runs sampled)

Benchmark with 42 arguments (time):
minimist: 0.344ms
larser: 0.08ms
mri: 0.046ms
nopt: 0.032ms
yargs: 0.779ms

With the following hardware:

• Processor: AMD Ryzen 5 3400G with Radeon Vega Graphics
• Total Physical Memory: 14,246 MB
• Windows version: Windows 11 Pro 22H2