puchi

A small JavaScript library to encode and decode large integer strings of base n <= 64 to base 64.

About

Puchi is a small and simple library that allows you to convert large integer strings of base n to base 64. One use case would be to convert MongoDB's ObjectID (12-byte, base 16) to base 64 for a url-shortener.

It also allows you to convert non-integer strings of base n to base n using the convert function. I'm not sure if that's all useful but it's there anyways 😆. See below for an example.

Note: This library depends on big-integer to perform large integer calculations.

encode(value: string, base?: number = 16)

• value - The integer string to encode.
• base - The base or radix of the integer string.

const { encode } = require('puchi');
 
console.log(encode("5c2bd2c156ddf30c73b39953")) // → n2LiMlrtYMNPIVBj

decode(value: string, base?: number = 16)

• value - The integer string to decode.
• base - The base or radix of the integer string.

const { decode } = require('puchi');
 
console.log(decode("n2LiMlrtYMNPIVBj")) // → 5c2bd2c156ddf30c73b39953

convert(value: string, from!: number, to!: number, domain?: string[], range?: string[])

• value - The integer string to convert.
• from - The base or radix of the integer string. (required)
• to - The base or radix to convert to. (required)
• domain - The domain or character map. Defaults to an array of 64 characters: [0-9, a-z, A-Z, '_', '-']
• range - The range or character map. Defaults to an array of 64 characters: [0-9, a-z, A-Z, '_', '-']

const { convert } = require('puchi')
 
console.log(convert('12345', 10, 2)) // → 11000000111001
 
console.log(convert('11000000111001', 2, 10)) // → 12345
 
 
// Note: The following example does not output in the ASCII sense of binary
// but more of a theoretical mapping.
 
const domain = "abcdefghijklmnopqrstuvwxyz !".split('');
console.log(convert("hello world!", domain.length, 2, domain)) 
// → 11010010111000111010110000111100010001011010100111011111
 
const range = domain;
console.log(convert(
  "11010010111000111010110000111100010001011010100111011111",
  2, range.length, null, range))
  hello world!