unenv/runtime/node/buffer/_base64.mjs

`unenv` is a framework-agnostic system that allows converting JavaScript code to be platform agnostic and work in any environment including Browsers, Workers, Node.js, or JavaScript runtime.

const lookup = [];
const revLookup = [];
const Arr = typeof Uint8Array === "undefined" ? Array : Uint8Array;
const code = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
for (let i = 0, len = code.length; i < len; ++i) {
  lookup[i] = code[i];
  revLookup[code.charCodeAt(i)] = i;
}
revLookup["-".charCodeAt(0)] = 62;
revLookup["_".charCodeAt(0)] = 63;
function getLens(b64) {
  const len = b64.length;
  if (len % 4 > 0) {
    throw new Error("Invalid string. Length must be a multiple of 4");
  }
  let validLen = b64.indexOf("=");
  if (validLen === -1) {
    validLen = len;
  }
  const placeHoldersLen = validLen === len ? 0 : 4 - validLen % 4;
  return [validLen, placeHoldersLen];
}
export function byteLength(b64) {
  const lens = getLens(b64);
  const validLen = lens[0];
  const placeHoldersLen = lens[1];
  return (validLen + placeHoldersLen) * 3 / 4 - placeHoldersLen;
}
function _byteLength(b64, validLen, placeHoldersLen) {
  return (validLen + placeHoldersLen) * 3 / 4 - placeHoldersLen;
}
export function toByteArray(b64) {
  let tmp;
  const lens = getLens(b64);
  const validLen = lens[0];
  const placeHoldersLen = lens[1];
  const arr = new Arr(_byteLength(b64, validLen, placeHoldersLen));
  let curByte = 0;
  const len = placeHoldersLen > 0 ? validLen - 4 : validLen;
  let i;
  for (i = 0; i < len; i += 4) {
    tmp = revLookup[b64.charCodeAt(i)] << 18 | revLookup[b64.charCodeAt(i + 1)] << 12 | revLookup[b64.charCodeAt(i + 2)] << 6 | revLookup[b64.charCodeAt(i + 3)];
    arr[curByte++] = tmp >> 16 & 255;
    arr[curByte++] = tmp >> 8 & 255;
    arr[curByte++] = tmp & 255;
  }
  if (placeHoldersLen === 2) {
    tmp = revLookup[b64.charCodeAt(i)] << 2 | revLookup[b64.charCodeAt(i + 1)] >> 4;
    arr[curByte++] = tmp & 255;
  }
  if (placeHoldersLen === 1) {
    tmp = revLookup[b64.charCodeAt(i)] << 10 | revLookup[b64.charCodeAt(i + 1)] << 4 | revLookup[b64.charCodeAt(i + 2)] >> 2;
    arr[curByte++] = tmp >> 8 & 255;
    arr[curByte++] = tmp & 255;
  }
  return arr;
}
function tripletToBase64(num) {
  return lookup[num >> 18 & 63] + lookup[num >> 12 & 63] + lookup[num >> 6 & 63] + lookup[num & 63];
}
function encodeChunk(uint8, start, end) {
  let tmp;
  const output = [];
  for (let i = start; i < end; i += 3) {
    tmp = (uint8[i] << 16 & 16711680) + (uint8[i + 1] << 8 & 65280) + (uint8[i + 2] & 255);
    output.push(tripletToBase64(tmp));
  }
  return output.join("");
}
export function fromByteArray(uint8) {
  let tmp;
  const len = uint8.length;
  const extraBytes = len % 3;
  const parts = [];
  const maxChunkLength = 16383;
  for (let i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
    parts.push(
      encodeChunk(
        uint8,
        i,
        i + maxChunkLength > len2 ? len2 : i + maxChunkLength
      )
    );
  }
  if (extraBytes === 1) {
    tmp = uint8[len - 1];
    parts.push(lookup[tmp >> 2] + lookup[tmp << 4 & 63] + "==");
  } else if (extraBytes === 2) {
    tmp = (uint8[len - 2] << 8) + uint8[len - 1];
    parts.push(
      lookup[tmp >> 10] + lookup[tmp >> 4 & 63] + lookup[tmp << 2 & 63] + "="
    );
  }
  return parts.join("");
}