fetch

  getRoute = () => {

    let addressDict = new Map();

    for (student of sampleData.studentList) {
      addressDict.set(student.studentID, student.address);
    }
    let wpoints_array = Array.from(addressDict.values());
    let wpoints_query = "";
    for (wp of wpoints_array) {
      wpoints_query += wp + "|";
    }
    wpoints_query = wpoints_query.substring(0, wpoints_query.length - 1);

    let origin_coords = this.state.longitude.toString() + ',' + this.state.latitude.toString();
    let destination = 'Muradiye Mah. Manolya Sokak No:234 Yunusemre - Manisa';
    let q_url = "https://maps.googleapis.com/maps/api/directions/json?origin=" + origin_coords;
    q_url += "&destination=" + destination;
    q_url += "&waypoints=" + wpoints_query;
    q_url += "&optimizeWaypoints=true";
    q_url += "&travelMode=DRIVING";
    q_url += "&key=AIzaSyCOqYI7eM7halH9qb10BmTGbrtrqfgBUw4";

    console.log("q_url: " + encodeURI(q_url));


    fetch(encodeURI(q_url))
      .then(function (response) {
        return response.json();
      })
      .then((response) => {
        console.log("responsejson: " + JSON.stringify(response));

        //alert("responseJson: " + JSON.stringify(responseJson));
        let url = 'http://maps.google.com/maps?saddr=' + origin_coords;
        for (let index = 0; index < response.routes[0].waypoint_order.length; index++) {
          let element = response.routes[0].waypoint_order[index];
          let addr = wpoints_array[element];

          if (index === 0)
            url += "&daddr=" + addr;
          else
            url += "+to:" + addr;
        }

        url += "+to:Muradiye Mah. Manolya Sokak No:234 Yunusemre - Manisa&dirflg=d";
        console.log("url : " + encodeURI(url));
        Linking.openURL(encodeURI(url));
      });
  };

Possible Unhandled Promise Rejection (id: 0):
ReactNativeJS: TypeError: undefined is not an object (evaluating 'response.routes[0]')

example q_url:
https://maps.googleapis.com/maps/api/directions/json?origin=38.43882333333333,27.202935000000004&destination=Muradiye%20Mah.%20Manolya%20Sokak%20No:234%20Yunusemre%20-%20Manisa&waypoints=1901.%20Sk.%20No:43,%20Saruhan%20Mahallesi,%2045010%20Manisa%20Merkez/Manisa,%20Türkiye|Oktay%20Erol%20Pulcuoğlu%20Cd.%20No:8,%2045030%20Keçiliköy%20Osb/Manisa%20Merkez/Manisa,%20Türkiye|Manisa%20TOKİ%20Konutları%20No:3,%20Uncubozköy%20Mahallesi,%2045030%20Manisa%20Merkez/Manisa,%20Türkiye|5619.%20Sk.%20No:2,%20Keçili%20Köy%20Mahallesi,%2045030%20Manisa%20Merkez/Manisa,%20Türkiye|Vali%20Azizbey%20Cd.%20No:34,%2075.%20Yıl%20Mahallesi,%2045030%20Manisa%20Merkez/Manisa,%20Türkiye|43.%20Sk.%20No:23,%20Turgut%20Özal%20Mahallesi,%2045040%20Manisa%20Merkez/Manisa,%20Türkiye|308.%20Sk.%20No:130,%20Kazım%20Karabekir%20Mahallesi,%2045040%20Şehzadeler/Manisa,%20Türkiye|1803.%20Sk.%20No:7,%20Çarşı%20Mahallesi,%2045010%20Manisa%20Merkez/Manisa,%20Türkiye&optimizeWaypoints=true&travelMode=DRIVING&key=AIzaSyCOqYI7eM7halH9qb10BmTGbrtrqfgBUw4