Fast mass replace in text by JavaScript when sed processor don't understand Unicode

notes_to_tabs.js

var fs = require('fs');

const notesToTabs = [
  { key: '𝄢[до]', val: 'Z' },
  { key: '𝄢[ре]', val: 'X' },
  { key: '𝄢[ми]', val: 'C' },
  { key: '𝄢[фа]', val: 'V' },
  { key: '𝄢[соль]', val: 'B' },
  { key: '𝄢[ля]', val: 'N' },
  { key: '𝄢[си]', val: 'M' },
  { key: '𝄡[до]', val: 'A' },
  { key: '𝄡[ре]', val: 'S' },
  { key: '𝄡[ми]', val: 'D' },
  { key: '𝄡[фа]', val: 'F' },
  { key: '𝄡[соль]', val: 'G' },
  { key: '𝄡[ля]', val: 'H' },
  { key: '𝄡[си]', val: 'J' },
  { key: '𝄞[до]', val: 'Q' },
  { key: '𝄞[ре]', val: 'W' },
  { key: '𝄞[ми]', val: 'E' },
  { key: '𝄞[фа]', val: 'R' },
  { key: '𝄞[соль]', val: 'T' },
  { key: '𝄞[ля]', val: 'Y' },
  { key: '𝄞[си]', val: 'U' }
];

const notesToPs4Old = [
  { key: '[до]', val: '🡄' },
  { key: '[ре]', val: '🡅' },
  { key: '[ми]', val: '🡆' },
  { key: '[фа]', val: '🡇' },
  { key: '[соль]', val: '□' },
  { key: '[ля]', val: '△' },
  { key: '[си]', val: '○' }
];

const notesToPs4 = [
  { key: '[до]', val: '←' },
  { key: '[ре]', val: '↑' },
  { key: '[ми]', val: '→' },
  { key: '[фа]', val: '↓' },
  { key: '[соль]', val: '□' },
  { key: '[ля]', val: '△' },
  { key: '[си]', val: '○' }
];

function replaceAll (input, from, to) {
  const fromLen = from.length;
  let output = '';
  let pos = 0;
  for (; ;) {
    let matchPos = input.indexOf(from, pos);
    if (matchPos === -1) {
      output += input.slice(pos);
      break;
    }
    output += input.slice(pos, matchPos);
    output += to;
    pos = matchPos + fromLen;
  }
  return output;
}

function formatLine (line, tabulation) {
  for (var i = 0; i < tabulation.length; i++) {
    line = replaceAll(line, tabulation[i].key, tabulation[i].val);
  }
  return line;
}

function reverseFormatLine (line, tabulation) {
  for (var i = 0; i < tabulation.length; i++) {
    line = replaceAll(line, tabulation[i].val, tabulation[i].key);
  }
  return line;
}

function processFile (inputFileName, mode, formatter) {
  var readline = require('readline'),
    instream = fs.createReadStream(`${inputFileName}.${isReverse ? mode : 'notes'}.txt`),
    outstream = new (require('stream'))(),
    rl = readline.createInterface(instream, outstream);
  formatted = '';
  rl.on('line', function (line) {
    switch (mode) {
      case 'ps4': {
        formatted += formatter(line, notesToPs4);
        break;
      }
      case 'ps4-old': {
        formatted += formatter(line, notesToPs4Old);
        break;
      }
      default: {
        formatted += formatter(line, notesToTabs);
        break;
      }
    }
    formatted += '\n';
  });
  rl.on('close', function (_line) {
    fs.writeFile(
      `${inputFileName}.${isReverse ? 'notes' : (mode === 'ps4-old' ? 'ps4' : mode)}.txt`, formatted, 'utf8',
      function (err) {
        if (err) {
          return console.log(err);
        }
      }
    );
  });
}

if (process.argv.length < 3) {
  console.log('Usage: node ' + process.argv[1] + ' FILENAME');
  process.exit(1);
}
var filename = process.argv[2], mode = process.argv[3] || 'notes',
  isReverse = process.argv[4] && process.argv[4] === 'reverse';
fs.readFile(
  `${filename}.${isReverse ? (mode === 'ps4-old' ? 'ps4' : mode) : 'notes'}.txt`, 'utf8', function (err, _data) {
    if (err) {
      throw err;
    }
    console.log('OK: ' + filename);
    processFile(filename, mode, isReverse ? reverseFormatLine : formatLine);
  });