pebble_tutorials/create_a_c_watchface/src/js/pebble-js-app.js

var xhrRequest = function (url, type, callback) {

  var xhr = new XMLHttpRequest();

  xhr.onload = function () {
    callback(this.responseText);
  };

  xhr.open(type, url);
  xhr.send();

};


function locationSuccess(pos) {

  // generic API key, has to be replaced by developers one
  var api_key = 'bd82977b86bf27fb59a04b61b657fb6f';

  // Construct URL
  var url = 'http://api.openweathermap.org/data/2.5/weather?lat=' +
      pos.coords.latitude + '&lon=' + pos.coords.longitude +
      '&APPID=' + api_key;

  // Send request to OpenWeatherMap
  xhrRequest(url, 'GET',
    function(responseText) {
      // responseText contains a JSON object with weather info
      var json = JSON.parse(responseText);

      // Temperature in Kelvin requires adjustment
      var temperature = Math.round(json.main.temp - 273.15);
      console.log('Temperature is ' + temperature);

      // Conditions
      var conditions = json.weather[0].main;
      console.log('Conditions are ' + conditions);

      // Assemble dictionary using our keys
      var dictionary = {
        'KEY_TEMPERATURE': temperature,
        'KEY_CONDITIONS': conditions
      };

      // Send to Pebble
      Pebble.sendAppMessage(dictionary,
        function(e) {
          console.log('Weather info sent to Pebble successfully!');
        },
        function(e) {
          console.log('Error sending weather info to Pebble!');
        }
      );
    }
  );

}


function locationError(err) {

  console.log('Error requesting location!');

}


function getWeather() {

  navigator.geolocation.getCurrentPosition(
    locationSuccess,
    locationError,
    {timeout: 15000, maximumAge: 60000}
  );

}


// Listen for when the watchface is opened
Pebble.addEventListener('ready',
  function(e) {
    console.log('PebbleKit JS ready!');
  // Get the initial weather
  getWeather();
  }
);


// Listen for when an AppMessage is received
Pebble.addEventListener('appmessage',
  function(e) {
    console.log('AppMessage received!');
    getWeather();
  }
);