Fast, lexicographic base62 encode and decode
# using npm
npm i --save lex62ts
# or using yarn
yarn add -D lex62ts- ideas from http://www.zanopha.com/docs/elen.pdf
- lexigraphical order: A < Z < a < z < 0 < 9
- ensures lexicographical order by appending an alphabetic prefix (based on number of digits).
decodewill only work with base64 numbers that have an expected prefix (alphabetic prefix appended to ensure lexigraphic order).encodeshould work with any safe positive integer (and zero) as long as it is not very large ~> 1e90 (see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger).
This library is written in and therefore fully supports Typescript. The commonjs module is compiled for Node16 and tested with Node14, 16 and 18.
import { encode } from 'lex62ts'
encode(0) // 'A0'
encode(1) // 'A1'
encode(9) // 'A9'
encode(10) // 'AA'
encode(35) // 'AZ'
encode(36) // 'Aa'
encode(61) // 'Az'
encode(62) // 'B10'
encode(123) // 'B1z'
encode(3843) // 'Bzz'
encode(3844) // 'C100'
encode(238327) // 'Czzz'
// errors
encode('yo')
// throws [Error: 'encode: invalid number (not an integer)']
encode(-10)
// throws [Error: 'encode: unsupported number (must be a positive integer or zero)']
encode(1e90)
// throws [Error: 'encode: unsupported number (too large)']- decode only works w/ base62 numbers which follow the format outputted by encode.
import { decode } from 'lex62ts'
decode('A0') // 0
decode('A1') // 1
decode('A9') // 9
decode('AA') // 10
decode('AZ') // 35
decode('Aa') // 36
decode('Az') // 61
decode('B10') // 62
decode('B1z') // 123
decode('Bzz') // 3843
decode('C100') // 3844
decode('Czzz') // 238327
// errors
decode('A*')
// throws [Error: 'decode: invalid string ("A*" not base62)']
decode('B0')
// throws [Error: 'decode: unsupported number (unexpected prefix)']
decode('B00')
// throws [Error: 'decode: unsupported number (unexpected zero)']
decode('zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz')
// throws [Error: 'decode: unsupported number (too large)']MIT