@hugov/shorter-string

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