@borderless/base64/dist.es2015/index.js

Base64 encoding and decoding for ArrayBuffer

/**
 * Original source: https://github.com/niklasvh/base64-arraybuffer.
 */
const base64Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
const base64UrlChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
const base64Lookup = new Uint8Array(256);
for (let i = 0; i < base64Chars.length; i++) {
    base64Lookup[base64Chars.charCodeAt(i)] = i;
}
// Support base64url.
base64Lookup[45 /* - */] = 62;
base64Lookup[95 /* _ */] = 63;
/**
 * Encode an `ArrayBuffer` to base64.
 */
export function encode(buffer, chars = base64Chars, padding = "=") {
    const bytes = new Uint8Array(buffer);
    const length = bytes.length;
    let base64 = "";
    for (let i = 0; i < length; i += 3) {
        base64 += chars[bytes[i] >> 2];
        base64 += chars[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)];
        base64 += chars[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)];
        base64 += chars[bytes[i + 2] & 63];
    }
    if (length % 3 === 2) {
        base64 = base64.slice(0, base64.length - 1) + padding;
    }
    else if (length % 3 === 1) {
        base64 = base64.slice(0, base64.length - 2) + padding + padding;
    }
    return base64;
}
/**
 * Encode using the base64url variant.
 */
export function encodeUrl(buffer) {
    return encode(buffer, base64UrlChars, "");
}
/**
 * Decode a base64 encoded string.
 */
export function decode(base64, lookup = base64Lookup) {
    const length = base64.length;
    let bufferLength = Math.floor(base64.length * 0.75);
    let p = 0;
    if (base64[length - 1] === "=") {
        bufferLength--;
        if (base64[length - 2] === "=") {
            bufferLength--;
        }
    }
    const bytes = new Uint8Array(bufferLength);
    for (let i = 0; i < length; i += 4) {
        const encoded1 = lookup[base64.charCodeAt(i)];
        const encoded2 = lookup[base64.charCodeAt(i + 1)];
        const encoded3 = lookup[base64.charCodeAt(i + 2)];
        const encoded4 = lookup[base64.charCodeAt(i + 3)];
        bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
        bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
        bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
    }
    return bytes;
}
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