Latitude and longitude normalization

latLngNormalization.js

// ASIDE: This was built during NodeKO 2012 -- hence the window.'s lying around

// Define latLngPadder
function normalizeLat(lat) {
  var latStr = lat + '';

  // Guarantee a decimal place in the number
  if (latStr.indexOf('.') === -1) {
    latStr = latStr + '.';
  }

  // Pad out to 4 decimal places
  latStr = latStr.replace(/(\.\d{0,3})$/, function (_, decimal) {
    // Add on the missing amount of items
    var decimalPlaces = decimal.length - 1,
        i = 0,
        len = 4 - decimalPlaces;
    for (; i < len; i++) {
      decimal += '0';
    }
    return decimal;
  });

  // Truncate off excess decimal places
  latStr = latStr.replace(/(\.\d{4})\d*$/, function (_, decimal) {
    return decimal;
  });

  // Return the latStr
  return latStr;
}

// Define window.properLat and window.properLng
window.properLat = function (lat) {
  // Fallback lat
  if (lat === undefined) { lat = window.lat; }

  // Convert lat to a number and determine direction
  var latNum = +lat,
      isNonNegative = latNum >= 0,
      direction = isNonNegative ? 'N' : 'S';

  // Get the absolute value and output it
  var absLat = Math.abs(latNum),
      normalLat = normalizeLat(absLat),
      properLat = normalLat + direction;
  return properLat;
};

// Define window.properLng
window.properLng = function (lng) {
  // Fallback lng
  if (lng === undefined) { lng = window.lng; }

  // Convert lng to a number and determine direction
  var latNum = +lng,
      isNonNegative = latNum >= 0,
      direction = isNonNegative ? 'E' : 'W';

  // Get the absolute value and output it
  var absLng = Math.abs(latNum),
      normalLng = normalizeLat(absLng),
      properLng = normalLng + direction;
  return properLng;
};

z_example.js

// Normalize lat and lng to 4 decimal places with direction
normalizeLat(100.000000002); // Normalizes -> 100.0000N
normalizeLng(100); // Normalizes -> 100.0000E
normalizeLat(-90.0001); // Normalizes -> 90.0001S
normalizeLng(-20.20); // Normalizes -> 20.2000W