base85

Pretty fast base85 JavaScript library (with TS support).

It is designed to encode binary data (Uint8Array) into a "base85" text string and vice versa.

npm install @alttiri/base85

API

function encode(ui8a: Uint8Array, charset?: "ascii85" | "z85" | string): string

encode encodes the input Uint8Array into base85 string.

function decode(base85: string, charset?: "ascii85" | "z85" | string): Uint8Array

decode decodes the input base85 string into Uint8Array.

charset is "z85" by default.

Also, there are encodeBase85 and decodeBase85 aliases for encode and decode functions.

Examples

Binary data encoding example:

import {encodeBase85} from "@alttiri/base85";

// png image, 169 bytes
const imageBytes = new Uint8Array([137,80,78,71,13,10,26,10,0,0,0,13,73,72,68,82,0,0,0,32,0,0,0,32,8,2,0,0,0,252,24,237,163,0,0,0,1,115,82,71,66,0,174,206,28,233,0,0,0,4,103,65,77,65,0,0,177,143,11,252,97,5,0,0,0,9,112,72,89,115,0,0,14,195,0,0,14,195,1,199,111,168,100,0,0,0,62,73,68,65,84,72,75,237,210,49,10,0,48,8,197,80,239,127,105,187,252,161,208,150,32,93,243,86,149,44,86,191,213,33,131,9,3,200,0,50,128,12,160,92,74,63,242,77,55,217,216,100,48,97,0,25,64,6,144,1,208,189,0,183,189,228,126,66,93,37,1,0,0,0,0,73,69,78,68,174,66,96,130]);
const base85 = encodeBase85(imageBytes);

console.log(base85);
console.log(base85.length);
// "Ibl@q4gj0X0000dnK#lE0000w0000w2M:#a0q)Y3Qw$n]0DRdeliagl9o^C600D}2o*F:VV5Yp<vfDSh010Qns-TMy4-nnD4-ns/z(vgD002hOl{T^yoypdZ3ih:=-zD2Mx$Kqp^3t!W]h.bcr>)fdG9.U305x6kPJ>8N[>z6@/KMWA02X3aKo9.w0jPV5ENmr^0rr9107/QOm6n<:F="
// 212

---

If you need to encode a text (are you really need it?) use TextEncoder/TextDecoder.

const input = "Man is distinguished";
const inputBytes = utf8StringToArrayBuffer(input);
console.log(encode(inputBytes, "ascii85"));  // "9jqo^BlbD-BleB1DJ+*+F(f,q"
console.log(encode(inputBytes, "z85"));      // "o<}]Zx(+zcx(!xgzFa9aB7/b}"

const outputBytes = decode("9jqo^BlbD-BleB1DJ+*+F(f,q", "ascii85");
const output = arrayBufferToUtf8String(outputBytes);
console.log(output); // "Man is distinguished"

For more examples see the tests.

---

You can test the lib online in the browser's console: https://alttiri.github.io/base85/online

All required things are already in the global scope. (encode, decode; util functions: utf8StringToArrayBuffer and others.)

---

Note. The optimisation for "ascii85" by replacing "\0\0\0\0" by "z" instead of "!!!!!" and " " (4 spaces) by "y" instead of "+<VdL" is not supported.

Anyway nobody forbids you to do something like base85.replaceAll("!!!!!", "z") as well as to add "<~", "~>" manually if you need it.

---

*.d.ts

/** 85 unique characters string */
type CharSet = string;
/**
 * Returns Base85 string.
 * @param {Uint8Array} ui8a - input data to encode
 * @param {"ascii85" | "z85" | string} [charset="z85"] - 85 unique characters string
 * @return {string}
 * */
export declare function encode(ui8a: Uint8Array, charset?: "ascii85" | "z85" | CharSet): string;
/**
 * Decodes Base85 string.
 * @param {string} base85 - base85 encoded string
 * @param {"ascii85" | "z85" | string} [charset="z85"] - 85 unique characters string
 * @return {Uint8Array}
 * */
export declare function decode(base85: string, charset?: "ascii85" | "z85" | CharSet): Uint8Array;
/** Alias to `encode`. */
export declare const encodeBase85: typeof encode;
/** Alias to `decode`. */
export declare const decodeBase85: typeof decode;
declare const base85: {
    encode: typeof encode;
    decode: typeof decode;
    encodeBase85: typeof encode;
    decodeBase85: typeof decode;
};
export default base85;

---

Installation

From NPM

npm install @alttiri/base85

From GitHub repository

npm install git+https://github.com/alttiri/base85.git

More ways

From GitHub repository (a specific version):

• Based on SemVer:

  npm install git+https://github.com/alttiri/base85.git#semver:1.5.1

  Or add

  "@alttiri/base85": "github:alttiri/base85#semver:1.5.1"
  

  as dependencies in package.json file.

  See available tags.

• Based on a commit hash:

  npm install git+https://[email protected]/alttiri/base85.git#ca3217f3d1075b8ff0966e24437326a6c2537bbc

  Or add

  "@alttiri/base85": "github:alttiri/base85#ca3217f3d1075b8ff0966e24437326a6c2537bbc"
  

  as dependencies in package.json file.

  See available commits hashes.

From GitHub Packages:

To install you need first to create .npmrc file with @alttiri:registry=https://npm.pkg.github.com content:

echo @alttiri:registry=https://npm.pkg.github.com >> .npmrc

only then run

npm install @alttiri/base85

Note, that GitHub Packages requires to have also ~/.npmrc file (.npmrc in your home dir) with //npm.pkg.github.com/:_authToken=TOKEN content, where TOKEN is a token with the read:packages permission, take it here https://github.com/settings/tokens/new.