tessl/npm-js-base64

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

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Overview

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Files

String Encoding and Decoding

Name: tessl/npm-js-base64
Author: tessl

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

Capabilities

String to Base64 Encoding

Converts a UTF-8 string to Base64 with optional URL-safe encoding.

/**
 * Converts a UTF-8-encoded string to a Base64 string
 * @param src - The UTF-8 string to encode
 * @param urlsafe - If true, make the result URL-safe (RFC4648 §5)
 * @returns Base64 encoded string
 */
function encode(src: string, urlsafe?: boolean): string;

/**
 * Alias for encode function
 */
function toBase64(src: string, urlsafe?: boolean): string;

Usage Examples:

import { encode, toBase64 } from "js-base64";

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

// UTF-8 encoding (handles Unicode properly)
const utf8 = encode("小飼弾");
console.log(utf8); // "5bCP6aO85by+"

// URL-safe encoding
const urlSafe = encode("小飼弾", true);
console.log(urlSafe); // "5bCP6aO85by-" (note the trailing -)

// Using alias
const alias = toBase64("Hello World!");
console.log(alias); // "SGVsbG8gV29ybGQh"

URL-Safe Base64 Encoding

Convenience function for URL-safe Base64 encoding (RFC4648 §5).

/**
 * Converts a UTF-8-encoded string to URL-safe Base64 RFC4648 §5
 * @param src - The UTF-8 string to encode
 * @returns URL-safe Base64 encoded string (uses - and _ instead of + and /)
 */
function encodeURI(src: string): string;

/**
 * Alias for encodeURI function
 */
function encodeURL(src: string): string;

Usage Examples:

import { encodeURI, encodeURL } from "js-base64";

const text = "Hello+World/Test=";

// URL-safe encoding
const urlSafe = encodeURI(text);
console.log(urlSafe); // "SGVsbG8rV29ybGQvVGVzdD0"

// Using alias
const alias = encodeURL(text);
console.log(alias); // "SGVsbG8rV29ybGQvVGVzdD0"

// Comparison with regular encoding
const regular = encode(text);
console.log(regular); // "SGVsbG8rV29ybGQvVGVzdD0=" (with padding)
const urlSafeExplicit = encode(text, true);
console.log(urlSafeExplicit); // "SGVsbG8rV29ybGQvVGVzdD0" (no padding)

Base64 to String Decoding

Converts a Base64 string back to UTF-8, supporting both standard and URL-safe formats.

/**
 * Converts a Base64 string to a UTF-8 string
 * @param src - Base64 string (both normal and URL-safe are supported)
 * @returns Decoded UTF-8 string
 */
function decode(src: string): string;

/**
 * Alias for decode function
 */
function fromBase64(src: string): string;

Usage Examples:

import { decode, fromBase64 } from "js-base64";

// Basic decoding
const decoded = decode("SGVsbG8gV29ybGQh");
console.log(decoded); // "Hello World!"

// UTF-8 decoding
const utf8Decoded = decode("5bCP6aO85by+");
console.log(utf8Decoded); // "小飼弾"

// URL-safe decoding (automatically detected)
const urlSafeDecoded = decode("5bCP6aO85by-");
console.log(urlSafeDecoded); // "小飼弾"

// Works with or without padding
const withoutPadding = decode("SGVsbG8gV29ybGQ");
const withPadding = decode("SGVsbG8gV29ybGQ=");
console.log(withoutPadding); // "Hello World"
console.log(withPadding); // "Hello World"

// Using alias
const alias = fromBase64("SGVsbG8gV29ybGQh");
console.log(alias); // "Hello World!"

// Handles whitespace
const withSpaces = decode("SGVs bG8g V29y bGQh");
console.log(withSpaces); // "Hello World!"

Key Features

UTF-8 Safe: Properly handles Unicode characters, unlike native browser btoa/atob
Flexible Input: Accepts both padded and non-padded Base64 strings
Format Detection: Automatically handles both standard and URL-safe Base64 formats in decode
Whitespace Tolerant: decode function ignores whitespace in input strings
Cross-platform: Works consistently across browsers and Node.js environments