shorter-string

small string to string compression for short strings using Burrows-Wheeler transform (BWT), move to front (MTF) and Elias-gamma variable length encoding

• Example • API • Notes • License

Example

import {encode, decode} from './index.js'

const text = `Si six chasseurs savent chasser sans six chiens, soixante-six chasseurs savent chasser sans soixante-six chiens.`,

const code = encode(text)
// 'PFp_Dd#sCa;F/f+QjYY/IEqySuqvq2JQ&=a2*?org~9T+r.:qp,yW6q

console.log( decode(code) === text),  )
// true, with 50% compression in character length

API

exports | Note ------------------ | ------------------------------- string constants| BASE62 | 0-9A-Za-z BASE64 | BASE62 + -_ UNRESERVED | BASE62 + -._~; RFC 3986 base:66 PCHAR | UNRESERVED + %!$&'()*+,;=:@; RFC 3986 base:80 QUERY | PCHAR without ' for chrome base:79 RFC1924 | RFC1924 base:85 HASH | PCHAR + /?#; base:83 functions | encode | ( text:string, [keys:string=HASH] ) => code:string decode: | ( code:string, [keys:string=HASH] ) => text:string

Notes

• inpired from the blog post reddad.ca/2020/09/27/burrows-wheeler-revisited
• modified to facilitate URI friendly encoding
• optimized for short strings
• not optimized for large inputs
• other alternatives considered
  • lz-string (small but no es6 exports and not the best compression for URI components)
  • lzbase62 (better compression)
  • lzutf8 (best compression, too big at 68.5 kb minified, no es6 exports)

Live Demo

License

MIT © Hugo Villeneuve