module.exports = function utf8_encode(argString) {
  //  discuss at: https://locutus.io/php/utf8_encode/
  // original by: Webtoolkit.info (https://www.webtoolkit.info/)
  // improved by: Kevin van Zonneveld (https://kvz.io)
  // improved by: sowberry
  // improved by: Jack
  // improved by: Yves Sucaet
  // improved by: kirilloid
  // bugfixed by: Onno Marsman (https://twitter.com/onnomarsman)
  // bugfixed by: Onno Marsman (https://twitter.com/onnomarsman)
  // bugfixed by: Ulrich
  // bugfixed by: Rafał Kukawski (https://blog.kukawski.pl)
  // bugfixed by: kirilloid
  //   example 1: utf8_encode('Kevin van Zonneveld')
  //   returns 1: 'Kevin van Zonneveld'

  if (argString === null || typeof argString === 'undefined') {
    return ''
  }

  // .replace(/\r\n/g, "\n").replace(/\r/g, "\n");
  const string = argString + ''
  let utftext = ''
  let start
  let end
  let stringl = 0

  start = end = 0
  stringl = string.length
  for (let n = 0; n < stringl; n++) {
    let c1 = string.charCodeAt(n)
    let enc = null

    if (c1 < 128) {
      end++
    } else if (c1 > 127 && c1 < 2048) {
      enc = String.fromCharCode((c1 >> 6) | 192, (c1 & 63) | 128)
    } else if ((c1 & 0xf800) !== 0xd800) {
      enc = String.fromCharCode((c1 >> 12) | 224, ((c1 >> 6) & 63) | 128, (c1 & 63) | 128)
    } else {
      // surrogate pairs
      if ((c1 & 0xfc00) !== 0xd800) {
        throw new RangeError('Unmatched trail surrogate at ' + n)
      }
      const c2 = string.charCodeAt(++n)
      if ((c2 & 0xfc00) !== 0xdc00) {
        throw new RangeError('Unmatched lead surrogate at ' + (n - 1))
      }
      c1 = ((c1 & 0x3ff) << 10) + (c2 & 0x3ff) + 0x10000
      enc = String.fromCharCode((c1 >> 18) | 240, ((c1 >> 12) & 63) | 128, ((c1 >> 6) & 63) | 128, (c1 & 63) | 128)
    }
    if (enc !== null) {
      if (end > start) {
        utftext += string.slice(start, end)
      }
      utftext += enc
      start = end = n + 1
    }
  }

  if (end > start) {
    utftext += string.slice(start, stringl)
  }

  return utftext
}