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

``javascript
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.PdmyIa1Up%T%(+'K_jiUzi!=LTIkOd,C;>)

License

MIT © Hugo Villeneuve