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tessl/npm-js-base64

Yet another Base64 transcoder in pure-JS with comprehensive UTF-8 support and cross-platform compatibility

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js-base64

js-base64 is a comprehensive Base64 encoding and decoding library for JavaScript that works across all environments including browsers and Node.js. It provides UTF-8 safe encoding/decoding, URL-safe Base64 variants, binary data support through Uint8Array integration, and optional prototype extensions for convenient usage patterns.

Package Information

  • Package Name: js-base64
  • Package Type: npm
  • Language: TypeScript (compiled to JavaScript)
  • Installation: npm install js-base64

Core Imports

import { Base64, encode, decode, fromUint8Array, toUint8Array } from "js-base64";

For CommonJS:

const { Base64, encode, decode, fromUint8Array, toUint8Array } = require("js-base64");

Using the namespace object:

import { Base64 } from "js-base64";
// All functions available as Base64.encode(), Base64.decode(), etc.

Basic Usage

import { encode, decode, fromUint8Array, toUint8Array } from "js-base64";

// Basic string encoding/decoding
const encoded = encode("Hello World!");
console.log(encoded); // "SGVsbG8gV29ybGQh"

const decoded = decode(encoded);
console.log(decoded); // "Hello World!"

// UTF-8 safe encoding
const utf8Text = "小飼弾"; // Japanese text
const utf8Encoded = encode(utf8Text);
console.log(utf8Encoded); // "5bCP6aO85by+"

const utf8Decoded = decode(utf8Encoded);
console.log(utf8Decoded); // "小飼弾"

// Binary data support
const uint8Array = new Uint8Array([100, 97, 110, 107, 111, 103, 97, 105]);
const binaryEncoded = fromUint8Array(uint8Array);
console.log(binaryEncoded); // "ZGFua29nYWk="

const binaryDecoded = toUint8Array(binaryEncoded);
console.log(binaryDecoded); // Uint8Array(8) [100, 97, 110, 107, 111, 103, 97, 105]

Architecture

js-base64 is built around several key components:

  • Cross-platform Compatibility: Automatically detects environment capabilities (Buffer, TextEncoder/TextDecoder) and uses native functions when available, falling back to pure JavaScript polyfills
  • Multiple Export Patterns: Provides both individual function exports and a complete namespace object (Base64) for different usage preferences
  • UTF-8 Safety: Handles Unicode characters properly, unlike native btoa/atob which only work with binary strings
  • URL-Safe Variants: Supports RFC4648 §5 URL-safe Base64 encoding with - and _ instead of + and /
  • Optional Extensions: Prototype extensions can be added to String and Uint8Array for fluent method chaining

Capabilities

String Encoding and Decoding

Core functionality for converting UTF-8 strings to/from Base64, with support for both standard and URL-safe variants.

function encode(src: string, urlsafe?: boolean): string;
function decode(src: string): string;
function encodeURI(src: string): string;

String Operations

Binary Data Operations

Convert between Uint8Array and Base64 strings for handling binary data like images, files, and byte arrays.

function fromUint8Array(u8a: Uint8Array, urlsafe?: boolean): string;
function toUint8Array(a: string): Uint8Array;

Binary Data

Browser Compatibility Functions

Low-level functions that replicate browser btoa/atob behavior with cross-platform support and polyfills.

function atob(asc: string): string;
function btoa(bin: string): string;
function atobPolyfill(asc: string): string;
function btoaPolyfill(bin: string): string;

Browser Compatibility

Validation and Utility Functions

Validate Base64 strings and access version information.

function isValid(src: unknown): boolean;
const version: string;
const VERSION: string; // @deprecated

Validation and Utilities

Prototype Extensions

Optional methods that can be added to String.prototype and Uint8Array.prototype for fluent method chaining.

function extendString(): void;
function extendUint8Array(): void;
function extendBuiltins(): void;

Prototype Extensions

Types

// All functions are also available in the Base64 namespace object
interface Base64Namespace {
  version: string;
  VERSION: string; // @deprecated
  encode(src: string, urlsafe?: boolean): string;
  toBase64(src: string, urlsafe?: boolean): string; // alias for encode
  encodeURI(src: string): string;
  encodeURL(src: string): string; // alias for encodeURI
  decode(src: string): string;
  fromBase64(src: string): string; // alias for decode
  fromUint8Array(u8a: Uint8Array, urlsafe?: boolean): string;
  toUint8Array(a: string): Uint8Array;
  atob(asc: string): string;
  btoa(bin: string): string;
  atobPolyfill(asc: string): string;
  btoaPolyfill(bin: string): string;
  isValid(src: unknown): boolean;
  utob(u: string): string; // @deprecated
  btou(b: string): string; // @deprecated
  extendString(): void;
  extendUint8Array(): void;
  extendBuiltins(): void;
}

declare const Base64: Base64Namespace;
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tessl
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npmpkg:npm/js-base64@3.7.x
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