base37-string

Encode a string into a base-37 64-bit number

Installation

npm install base37-string --save

Usage

import { encode, decode } from "base37-string";

const encoded = encode("james"); // 0x00000000011F0598
const decoded = decode(encoded); // james

Algorithm

encode

1. Take a string x
2. Convert x into an array of character codes c[]
3. Initialise an accumulator acc as 0
4. Iterate through c[] for individual character codes c:
   • If 65 <= c <= 90, let i equal (1 + c) - 65
   • If 97 <= c <= 122, let i equal (1 + c) - 97
   • If 48 <= c <= 57, let i equal (27 + c) - 48
5. Multiply acc by 37 and add i
6. While acc is not 0 and is evenly divisible by 37, divide by 37
7. Return acc

decode

1. Take a long x which must not:
   • be <= 0
   • be >= 0x5b5b57f8a98a5dd1
   • be evenly divisible by 37
2. Initialice an accumulator acc as x
3. Initialise an array c[]
4. While acc is not 0:
   1. Store the value of acc as n
   2. Divide acc by 37
   3. let i equal n - acc * 37
   4. get value at index i from array of valid characters and push to front of c[]
5. Join c[] into string and return