// Copyright 2018-2025 the Deno authors. MIT license.
// This module is browser compatible.
/**
* Utilities for
* {@link https://www.rfc-editor.org/rfc/rfc4648.html#section-4 | base64}
* encoding and decoding.
*
* ```ts
* import {
* encodeBase64,
* decodeBase64,
* } from "@std/encoding/base64";
* import { assertEquals } from "@std/assert";
*
* const foobar = new TextEncoder().encode("foobar");
*
* assertEquals(encodeBase64(foobar), "Zm9vYmFy");
* assertEquals(decodeBase64("Zm9vYmFy"), foobar);
* ```
*
* @module
*/
import { calcSizeBase64, decode, encode } from "./_common64.ts";
import { detach } from "./_common_detach.ts";
import type { Uint8Array_ } from "./_types.ts";
export type { Uint8Array_ };
const padding = "=".charCodeAt(0);
const alphabet = new TextEncoder()
.encode("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/");
const rAlphabet = new Uint8Array(128).fill(64); // alphabet.length
alphabet.forEach((byte, i) => rAlphabet[byte] = i);
/**
* Converts data into a base64-encoded string.
*
* @see {@link https://www.rfc-editor.org/rfc/rfc4648.html#section-4}
*
* @param data The data to encode.
* @returns The base64-encoded string.
*
* @example Usage
* ```ts
* import { encodeBase64 } from "@std/encoding/base64";
* import { assertEquals } from "@std/assert";
*
* assertEquals(encodeBase64("foobar"), "Zm9vYmFy");
* ```
*/
export function encodeBase64(data: ArrayBuffer | Uint8Array | string): string {
if (typeof data === "string") {
data = new TextEncoder().encode(data) as Uint8Array_;
} else if (data instanceof ArrayBuffer) data = new Uint8Array(data).slice();
else data = data.slice();
const [output, i] = detach(
data as Uint8Array_,
calcSizeBase64((data as Uint8Array_).length),
);
encode(output, i, 0, alphabet, padding);
return new TextDecoder().decode(output);
}
/**
* Decodes a base64-encoded string.
*
* @see {@link https://www.rfc-editor.org/rfc/rfc4648.html#section-4}
*
* @param b64 The base64-encoded string to decode.
* @returns The decoded data.
*
* @example Usage
* ```ts
* import { decodeBase64 } from "@std/encoding/base64";
* import { assertEquals } from "@std/assert";
*
* assertEquals(
* decodeBase64("Zm9vYmFy"),
* new TextEncoder().encode("foobar")
* );
* ```
*/
export function decodeBase64(b64: string): Uint8Array_ {
const output = new TextEncoder().encode(b64) as Uint8Array_;
// deno-lint-ignore no-explicit-any
return new Uint8Array((output.buffer as any)
.transfer(decode(output, 0, 0, rAlphabet, padding)));
}
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