deBOM.js

'use strict';
/******************************************************************************/
const path = process.argv[2];
if (!path) {
  console.log('Add the file path, please.');
  process.exit();
}
/******************************************************************************/
const fs = require('fs');

const rl = require('readline').createInterface({
  input: fs.createReadStream(path, 'utf8'), //ascii utf8 utf16le
  terminal: false,
  historySize: 0
});

const outfile =  fs.openSync(path.replace(/(\.[^.]+)?$/, '.new$1'), 'w');

let   lines = 0;
/******************************************************************************/
rl.on('line', function(line) {
  lines++;
  if (lines === 1) line = line.replace(/^\uFEFF/, '');
	fs.writeSync(outfile, `${line}\n`, null, 'utf8');
});
/******************************************************************************/