coords.js

function parseDD(line) {
  const re = /^\D*?(-?[0-9]+(?:[.,][0-9]{1,20})?)[,\s]+(-?[0-9]+(?:[.,][0-9]{1,20})?)\D*$/;
  const match = re.exec(line.trim());
  if (!match) {
    return false;
  }
  var lat = parseFloat(match[1].replace(',', '.'));
  var lon = parseFloat(match[2].replace(',', '.'));
  if (Math.abs(lat) > 90 || Math.abs(lon) > 180) {
    return false;
  }
  return {'lat': lat, 'lon': lon};
}

function parseWSG84(line) {
  const re = /^\D*([NS])\s*(\d{1,2}).\s*(\d{1,2}(?:[.,]\d{1,4})?)'?[,\s/\\]+([EW])\s*(\d{1,3}).\s*(\d{1,2}(?:[.,]\d{1,4})?)'?\D*$/;
  const match = re.exec(line.trim());
  if (!match) {
    return false;
  }
  const latDeg = parseInt(match[2], 10);
  const lonDeg = parseInt(match[5], 10);
  if (latDeg > 90 || lonDeg > 180) {
    return false;
  }

  const latMin = parseFloat(match[3].replace(',', '.'));
  const lonMin = parseFloat(match[6].replace(',', '.'));

  return {
    'lat': match[1], 'lat_deg': latDeg, 'lat_min': latMin,
    'lon': match[4], 'lon_deg': lonDeg, 'lon_min': lonMin
  };
}

function checkGlue(glue) {
  var newGlue = ', ';
  if (typeof glue === 'undefined') {
    newGlue = ', ';
  } else {
    newGlue = glue;
  }
  return newGlue;
}

/**
 * @returns {string}
 * @param {string} lat
 * @param {number} latDeg
 * @param {number} latMin
 * @param {string} lon
 * @param {number} lonDeg
 * @param {number} lonMin
 * @param {string} _glue
 */
function WGS84toDD(lat, latDeg, latMin, lon, lonDeg, lonMin, _glue) {
  var glue = checkGlue(_glue);

  var la = latDeg + (latMin / 60);
  var lo = lonDeg + (lonMin / 60);
  if (lat === 'S') la = -la;
  if (lon === 'W') lo = -lo;

  return la.toFixed(5) + glue + lo.toFixed(5);
}

/**
 * @returns {string}
 * @param {number} _lat
 * @param {number} _lon
 * @param {string} _glue symbols used to glue lat and lon together in result string
 */
function DDtoWGS84(_lat, _lon, _glue) {
  var glue = checkGlue(_glue);

  var latLetter = _lat >= 0 ? 'N' : 'S';
  var lotLetter = _lon >= 0 ? 'E' : 'W';

  var lat = Math.abs(_lat);
  var lon = Math.abs(_lon);

  var latDeg = Math.floor(lat);
  var lonDeg = Math.floor(lon);

  var latMin = (lat - latDeg) * 60;
  var lonMin = (lon - lonDeg) * 60;

  // \xB0 is °
  return latLetter + ' ' + latDeg + '\xB0 ' + latMin.toFixed(3) + "'" + glue +
    lotLetter + ' ' + lonDeg + '\xB0 ' + lonMin.toFixed(3) + "'";
}

function transformCoordinatesString(line, glue) {
  var coordsFrom = line.trim();
  var coordsTo = coordsFrom;

  var res = parseWSG84(coordsFrom);
  if (res) {
    coordsTo = WGS84toDD(res.lat, res.lat_deg, res.lat_min,
      res.lon, res.lon_deg, res.lon_min, glue);
  } else if (parseDD(coordsFrom)) {
    res = parseDD(coordsFrom);
    coordsTo = DDtoWGS84(res.lat, res.lon, glue);
  }
  return coordsTo;
}

function transformCoordinatesInElem(e, glue) {
  var coordsFrom = e.textContent.trim();
  e.innerHTML = transformCoordinatesString(coordsFrom, glue);
}

function transformCoordinatesInElemValue(e, glue) {
  var coordsFrom = e.value.trim();
  e.value = transformCoordinatesString(coordsFrom, glue);
}

function transformCoordinatesInElemByIdValue(id, glue) {
  var elem = document.getElementById(id);
  var coordsFrom = elem.value.trim();
  elem.value = transformCoordinatesString(coordsFrom, glue);
}

function transformCoordinatesInElemById(id, glue) {
  var elem = document.getElementById(id);
  transformCoordinatesInElem(elem, glue);
}

function transformCoordinatesInElemBySelector(selector, glue) {
  document.querySelectorAll(selector).forEach(function (item) {
    transformCoordinatesInElem(item, glue);
  });
}

if (typeof module !== 'undefined' && module.exports) {
  exports.parseDD = parseDD;
  exports.parseWSG84 = parseWSG84;

  exports.DDtoWGS84 = DDtoWGS84;
  exports.WGS84toDD = WGS84toDD;

  exports.transformCoordinatesString = transformCoordinatesString;
}