Utility function for checking if something exists.

gistfile1.js

// Check existence
function exists(thing) {
  return (!isNaN(thing) && typeof thing !== 'undefined' && thing !== null) ? thing : undefined;
}

// Or, more tersely
function exists(thing) {
  // != checks `null` and `undefined`
  return thing != null ? thing : undefined;
}

/*
  Usage...

  var options = {
    latitude: 0,
    longitude: 1
  };

  var lat = exists(options.latitude);
  var lon = exists(options.longitude);
*/

@getify Good call. Forgot about that.