Base64 Typescript

base64.ts

const newLocal =
  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
/* eslint-disable no-bitwise */
const keyStr = newLocal;

export const encode = (input: string) => {
  var output = [];
  var chr1, chr2, chr3;
  var enc1, enc2, enc3, enc4;
  var i = 0;

  do {
    chr1 = input.charCodeAt(i++);
    chr2 = input.charCodeAt(i++);
    chr3 = input.charCodeAt(i++);

    enc1 = chr1 >> 2;
    enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
    enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
    enc4 = chr3 & 63;

    if (isNaN(chr2)) {
      enc3 = enc4 = 64;
    } else if (isNaN(chr3)) {
      enc4 = 64;
    }

    output.push(
      keyStr.charAt(enc1) +
        keyStr.charAt(enc2) +
        keyStr.charAt(enc3) +
        keyStr.charAt(enc4)
    );
    chr1 = chr2 = chr3 = '';
    enc1 = enc2 = enc3 = enc4 = '';
  } while (i < input.length);

  return output.join('');
};

export const encodeFromByteArray = (input: Uint8Array) => {
  var output = [];
  var chr1, chr2, chr3;
  var enc1, enc2, enc3, enc4;
  var i = 0;

  do {
    chr1 = input[i++];
    chr2 = input[i++];
    chr3 = input[i++];

    enc1 = chr1 >> 2;
    enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
    enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
    enc4 = chr3 & 63;

    if (isNaN(chr2)) {
      enc3 = enc4 = 64;
    } else if (isNaN(chr3)) {
      enc4 = 64;
    }

    output.push(
      keyStr.charAt(enc1) +
        keyStr.charAt(enc2) +
        keyStr.charAt(enc3) +
        keyStr.charAt(enc4)
    );

    chr1 = chr2 = chr3 = '';
    enc1 = enc2 = enc3 = enc4 = '';
  } while (i < input.length);

  return output.join('');
};

export const decode = (input: string) => {
  var output = '';
  var chr1, chr2, chr3;
  var enc1, enc2, enc3, enc4;
  var i = 0;

  // remove all characters that are not A-Z, a-z, 0-9, +, /, or =
  // eslint-disable-next-line no-useless-escape
  var base64test = /[^A-Za-z0-9\+\/\=]/g;
  if (base64test.exec(input)) {
    throw new Error(
      'There were invalid base64 characters in the input text.\n' +
        "Valid base64 characters are A-Z, a-z, 0-9, '+', '/',and '='\n" +
        'Expect errors in decoding.'
    );
  }
  // eslint-disable-next-line no-useless-escape
  input = input.replace(/[^A-Za-z0-9\+\/\=]/g, '');

  do {
    enc1 = keyStr.indexOf(input.charAt(i++));
    enc2 = keyStr.indexOf(input.charAt(i++));
    enc3 = keyStr.indexOf(input.charAt(i++));
    enc4 = keyStr.indexOf(input.charAt(i++));

    chr1 = (enc1 << 2) | (enc2 >> 4);
    chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
    chr3 = ((enc3 & 3) << 6) | enc4;

    output = output + String.fromCharCode(chr1);

    if (enc3 !== 64) {
      output = output + String.fromCharCode(chr2);
    }
    if (enc4 !== 64) {
      output = output + String.fromCharCode(chr3);
    }

    chr1 = chr2 = chr3 = '';
    enc1 = enc2 = enc3 = enc4 = '';
  } while (i < input.length);

  return output;
};

export const decodeAsBytes = (input: string): Uint8Array => {
  let s = decode(input);
  let output: Uint8Array = new Uint8Array(s.length);

  s.split('').map((char, i) => {
    output[i] = char.charCodeAt(0);
  });

  return output;
};