random-browser-js

This module is used for generating cryptographically strong random numbers suitable for managing data such as passwords, account authentication, security tokens, and related secrets.

In particular, this should be used in preference to the default pseudo-random number generator Math.random(), which is designed for modelling and simulation, not security or cryptography.

Inspired by crypto from Node.js and secrets from Python.

Example

<script type="module">
import { choice, randomBits, randomBytes, randomInt, tokenHex, tokenUrlsafe } from 'https://cdn.jsdelivr.net/npm/random-browser';

console.log('Pick a random fruit from array: ' + choice(['Apple', 'Banana', 'Orange']));
console.log('Pick a random character from string: ' + choice('ABCDEF'));
console.log('Random integer with 4 random bits (<16): ' + randomBits(4));
console.log('3 random bytes e.g. [218, 82, 127]: ' + randomBytes(3));
console.log('Random number chosen from (0, 1, 2): ' + randomInt(3));
console.log('The dice rolled: ' + randomInt(1, 7));
console.log('32 character hexadecimal string from 16 random bytes: ' + tokenHex(16));
console.log('URL-safe Base64 text string from 32 random bytes: ' + tokenUrlsafe());
</script>

Install

Use a CDN like JSDelivr:

https://cdn.jsdelivr.net/npm/[email protected]
or
https://cdn.jsdelivr.net/npm/random-browser

Or you can download random.js from GitHub. Alternatively, you can install it via npm:

npm install random-browser

Features

• No dependencies or huge compiled files.
• No configuration.
• No need to choose between entropy sources.
• Minimizing footguns is a high priority.
• Just call the functions and you're all set.

Usage

choice(arr)

• arr <Array> The array containing the choices.
• Returns <Object>

Return a randomly-chosen element from a non-empty array arr.

choice(['Apple', 'Banana', 'Orange']);
choice('ABCDEF');

randomBits(k)

• k <integer> Number of bits.
• Returns <integer>

Return a random integer n with k random bits such that 0 <= n < 2k. The number of bits (k) must be less than or equal to 48.

randomBits(4);

randomBytes(size)

• size <integer> The number of bytes to generate.
• Returns: <Uint8Array>

Generates cryptographically strong pseudorandom data. The size argument is a number indicating the number of bytes to generate.

randomBytes(3);

randomInt([min, ]max)

• min <integer> Start of random range (inclusive). Default: 0.
• max <integer> End of random range (exclusive).
• Returns <integer>

Return a random integer n such that min <= n < max. The range (max - min) must be less than 248. min and max must be safe integers.

randomInt(3);
randomInt(1, 7);

tokenHex([numBytes])

• numBytes <integer> The number of bytes to generate. Default: 32.
• Returns: <string>

Return a random text string, in hexadecimal. The string has numBytes random bytes, each byte converted to two hex digits. If numBytes is not supplied, a reasonable default is used.

tokenHex();
tokenHex(16);

tokenUrlsafe([numBytes])

• numBytes <integer> The number of bytes to generate. Default: 32.
• Returns: <string>

Return a random URL-safe text string, containing numBytes random bytes. The text is Base64 encoded, so on average each byte results in approximately 1.3 characters. If numBytes is not supplied, a reasonable default is used.

tokenUrlsafe();
tokenUrlsafe(16);