multiformats/esm/src/bases/base64.js

Interface for multihash, multicodec, multibase and CID

import { withSettings } from './base.js';
const alphabetSettings = alphabet => ({
  alphabet,
  padding: alphabet.indexOf('=') > -1,
  url: alphabet.indexOf('-') > -1 && alphabet.indexOf('_') > -1
});
export default b64 => {
  const encode = (input, {url, padding}) => {
    let output = b64.encode(input);
    if (url) {
      output = output.replace(/\+/g, '-').replace(/\//g, '_');
    }
    const pad = output.indexOf('=');
    if (pad > 0 && !padding) {
      output = output.substring(0, pad);
    }
    return output;
  };
  const decode = (input, {alphabet}) => {
    for (const char of input) {
      if (alphabet.indexOf(char) < 0) {
        throw new Error('invalid base64 character');
      }
    }
    return b64.decode(input);
  };
  const codec = ({name, prefix, alphabet}) => withSettings({
    name,
    prefix,
    settings: alphabetSettings(alphabet),
    decode,
    encode
  });
  return {
    b64,
    __browser: b64.__browser,
    base64: codec({
      name: 'base64',
      prefix: 'm',
      alphabet: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
    }),
    base64pad: codec({
      name: 'base64pad',
      prefix: 'M',
      alphabet: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='
    }),
    base64url: codec({
      name: 'base64url',
      prefix: 'u',
      alphabet: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_'
    }),
    base64urlpad: codec({
      name: 'base64urlpad',
      prefix: 'U',
      alphabet: 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_='
    })
  };
};