Example of Javascript Geocode function using Mapquest Nominatim API

geocode.js

// Geocoding using Mapquest Nominatim API
// 
// Documentation for the API: http://wiki.openstreetmap.org/wiki/Nominatim
// Here's an example query: http://open.mapquestapi.com/nominatim/v1/search?q=detroit&format=json

// geocode function 
//
// :param place: is a place name like "Detroit" or "London"
// :callback: function receiving arguments (error, {lon: ..., lat: ...})
function geocode(place, callback) {
  var url = 'http://open.mapquestapi.com/search?format=json&q=' + encodeURIComponent(place);
  // requires jquery for ajax
  jQuery.getJSON(url, function(data) {
    if (data.length > 0) {
      callback(null, { lon: parseFloat(data[0].lon), lat: parseFloat(data[0].lat) })
    } else {
      callback(null, null)
    }
  });
}