Data Layer: Drag and Drop GeoJSON

This example allows you to drag and drop GeoJSON onto the map. Download a sample GeoJSON file to test dragging from the device.

For more information about how to work with the map data layer, see the google.maps.Data class.

TypeScript

let map: google.maps.Map;

function initMap(): void {
  // set up the map
  map = new google.maps.Map(document.getElementById("map") as HTMLElement, {
    center: new google.maps.LatLng(0, 0),
    zoom: 4,
  });
}

function loadGeoJsonString(geoString: string) {
  try {
    const geojson = JSON.parse(geoString) as any;

    map.data.addGeoJson(geojson);
  } catch (e) {
    alert("Not a GeoJSON file!");
  }

  zoom(map);
}

/**
 * Update a map's viewport to fit each geometry in a dataset
 */
function zoom(map: google.maps.Map) {
  const bounds = new google.maps.LatLngBounds();

  map.data.forEach((feature) => {
    const geometry = feature.getGeometry();

    if (geometry) {
      processPoints(geometry, bounds.extend, bounds);
    }
  });
  map.fitBounds(bounds);
}

/**
 * Process each point in a Geometry, regardless of how deep the points may lie.
 */
function processPoints(
  geometry: google.maps.LatLng | google.maps.Data.Geometry,
  callback: any,
  thisArg: google.maps.LatLngBounds
) {
  if (geometry instanceof google.maps.LatLng) {
    callback.call(thisArg, geometry);
  } else if (geometry instanceof google.maps.Data.Point) {
    callback.call(thisArg, geometry.get());
  } else {
    // @ts-ignore
    geometry.getArray().forEach((g) => {
      processPoints(g, callback, thisArg);
    });
  }
}

/* DOM (drag/drop) functions */
function initEvents() {
  [...document.getElementsByClassName("file")].forEach((fileElement) => {
    fileElement.addEventListener(
      "dragstart",
      (e: Event) => {
        // @ts-ignore
        e.dataTransfer.setData(
          "text/plain",
          JSON.stringify(files[Number((e.target as HTMLElement).dataset.value)])
        );
        console.log(e);
      },
      false
    );
  });

  // set up the drag & drop events
  const mapContainer = document.getElementById("map") as HTMLElement;

  mapContainer.addEventListener("dragenter", addClassToDropTarget, false);
  mapContainer.addEventListener("dragover", addClassToDropTarget, false);
  mapContainer.addEventListener("drop", handleDrop, false);
  mapContainer.addEventListener("dragleave", removeClassFromDropTarget, false);
}

function addClassToDropTarget(e: Event) {
  e.stopPropagation();
  e.preventDefault();
  document.getElementById("map")!.classList.add("over");
  return false;
}

function removeClassFromDropTarget(e: Event) {
  document.getElementById("map")!.classList.remove("over");
}

function handleDrop(e: DragEvent) {
  e.preventDefault();
  e.stopPropagation();
  removeClassFromDropTarget(e);

  const files = (e.dataTransfer as DataTransfer).files;

  if (files.length) {
    // process file(s) being dropped
    // grab the file data from each file
    for (let i = 0, file; (file = files[i]); i++) {
      const reader = new FileReader();

      reader.onload = function (e) {
        loadGeoJsonString(reader.result as string);
      };

      reader.onerror = function (e) {
        console.error("reading failed");
      };

      reader.readAsText(file);
    }
  } else {
    // process non-file (e.g. text or html) content being dropped
    // grab the plain text version of the data
    const plainText = (e.dataTransfer as DataTransfer).getData("text/plain");

    console.log(plainText);

    if (plainText) {
      loadGeoJsonString(plainText);
    }
  }

  // prevent drag event from bubbling further
  return false;
}

function initialize() {
  initMap();
  initEvents();
}

const files = [
  {
    type: "FeatureCollection",
    features: [
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Polygon",
          coordinates: [
            [
              [-99.49218749999999, -11.867350911459294],
              [24.960937499999996, -11.867350911459294],
              [24.960937499999996, 47.517200697839414],
              [-99.49218749999999, 47.517200697839414],
              [-99.49218749999999, -11.867350911459294],
            ],
          ],
        },
      },
    ],
  },
  {
    type: "FeatureCollection",
    features: [
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [81.2109375, 50.064191736659104],
        },
      },
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [103.35937499999999, -47.98992166741417],
        },
      },
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [-46.05468749999999, 64.01449619484472],
        },
      },
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [-113.203125, 37.996162679728116],
        },
      },
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [-73.828125, -32.249974455863295],
        },
      },
    ],
  },
  {
    type: "FeatureCollection",
    features: [
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "LineString",
          coordinates: [
            [147.65625, -5.266007882805485],
            [118.47656249999999, 43.83452678223682],
            [80.85937499999999, -30.145127183376115],
            [35.15625, 51.83577752045248],
            [-15.468749999999998, -23.563987128451217],
            [-29.53125, 44.33956524809713],
            [-73.47656249999999, -32.842673631954305],
            [-104.765625, 35.460669951495305],
          ],
        },
      },
    ],
  },
];

JavaScript

let map;

function initMap() {
  // set up the map
  map = new google.maps.Map(document.getElementById("map"), {
    center: new google.maps.LatLng(0, 0),
    zoom: 4,
  });
}

function loadGeoJsonString(geoString) {
  try {
    const geojson = JSON.parse(geoString);

    map.data.addGeoJson(geojson);
  } catch (e) {
    alert("Not a GeoJSON file!");
  }

  zoom(map);
}

/**
 * Update a map's viewport to fit each geometry in a dataset
 */
function zoom(map) {
  const bounds = new google.maps.LatLngBounds();

  map.data.forEach((feature) => {
    const geometry = feature.getGeometry();

    if (geometry) {
      processPoints(geometry, bounds.extend, bounds);
    }
  });
  map.fitBounds(bounds);
}

/**
 * Process each point in a Geometry, regardless of how deep the points may lie.
 */
function processPoints(geometry, callback, thisArg) {
  if (geometry instanceof google.maps.LatLng) {
    callback.call(thisArg, geometry);
  } else if (geometry instanceof google.maps.Data.Point) {
    callback.call(thisArg, geometry.get());
  } else {
    geometry.getArray().forEach((g) => {
      processPoints(g, callback, thisArg);
    });
  }
}

/* DOM (drag/drop) functions */
function initEvents() {
  [...document.getElementsByClassName("file")].forEach((fileElement) => {
    fileElement.addEventListener(
      "dragstart",
      (e) => {
        e.dataTransfer.setData(
          "text/plain",
          JSON.stringify(files[Number(e.target.dataset.value)])
        );
        console.log(e);
      },
      false
    );
  });

  // set up the drag & drop events
  const mapContainer = document.getElementById("map");

  mapContainer.addEventListener("dragenter", addClassToDropTarget, false);
  mapContainer.addEventListener("dragover", addClassToDropTarget, false);
  mapContainer.addEventListener("drop", handleDrop, false);
  mapContainer.addEventListener("dragleave", removeClassFromDropTarget, false);
}

function addClassToDropTarget(e) {
  e.stopPropagation();
  e.preventDefault();
  document.getElementById("map").classList.add("over");
  return false;
}

function removeClassFromDropTarget(e) {
  document.getElementById("map").classList.remove("over");
}

function handleDrop(e) {
  e.preventDefault();
  e.stopPropagation();
  removeClassFromDropTarget(e);

  const files = e.dataTransfer.files;

  if (files.length) {
    // process file(s) being dropped
    // grab the file data from each file
    for (let i = 0, file; (file = files[i]); i++) {
      const reader = new FileReader();

      reader.onload = function (e) {
        loadGeoJsonString(reader.result);
      };

      reader.onerror = function (e) {
        console.error("reading failed");
      };

      reader.readAsText(file);
    }
  } else {
    // process non-file (e.g. text or html) content being dropped
    // grab the plain text version of the data
    const plainText = e.dataTransfer.getData("text/plain");

    console.log(plainText);
    if (plainText) {
      loadGeoJsonString(plainText);
    }
  }
  // prevent drag event from bubbling further
  return false;
}

function initialize() {
  initMap();
  initEvents();
}

const files = [
  {
    type: "FeatureCollection",
    features: [
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Polygon",
          coordinates: [
            [
              [-99.49218749999999, -11.867350911459294],
              [24.960937499999996, -11.867350911459294],
              [24.960937499999996, 47.517200697839414],
              [-99.49218749999999, 47.517200697839414],
              [-99.49218749999999, -11.867350911459294],
            ],
          ],
        },
      },
    ],
  },
  {
    type: "FeatureCollection",
    features: [
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [81.2109375, 50.064191736659104],
        },
      },
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [103.35937499999999, -47.98992166741417],
        },
      },
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [-46.05468749999999, 64.01449619484472],
        },
      },
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [-113.203125, 37.996162679728116],
        },
      },
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "Point",
          coordinates: [-73.828125, -32.249974455863295],
        },
      },
    ],
  },
  {
    type: "FeatureCollection",
    features: [
      {
        type: "Feature",
        properties: {},
        geometry: {
          type: "LineString",
          coordinates: [
            [147.65625, -5.266007882805485],
            [118.47656249999999, 43.83452678223682],
            [80.85937499999999, -30.145127183376115],
            [35.15625, 51.83577752045248],
            [-15.468749999999998, -23.563987128451217],
            [-29.53125, 44.33956524809713],
            [-73.47656249999999, -32.842673631954305],
            [-104.765625, 35.460669951495305],
          ],
        },
      },
    ],
  },
];

CSS

html {
  height: 100%;
}

body {
  height: 100%;
  margin: 0;
  padding: 0;
  overflow: hidden;
}

#map {
  height: 100%;
}
#map.over {
  opacity: 0.5;
  background-color: rgba(100, 100, 100, 0.5);
}

#sidebar {
  flex-direction: column;
  align-items: center;
  justify-content: center;
  overflow: auto;
}

.file {
  display: flex;
  flex-flow: column;
  margin-top: 1em;
  cursor: move;
  text-align: center;
}
.file:hover .material-icons {
  color: darkorange;
}
.file:hover .filename {
  font-weight: bold;
}
.file .material-icons {
  font-size: 50px;
  color: orange;
}
.file .material-icons:hover {
  color: darkorange;
}
.file .filename {
  margin-top: 0.5em;
  font-size: 20px;
  color: #333333;
}

/* Optional: Makes the sample page fill the window. */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

#container {
  height: 100%;
  display: flex;
}

#sidebar {
  flex-basis: 15rem;
  flex-grow: 1;
  padding: 1rem;
  max-width: 30rem;
  height: 100%;
  box-sizing: border-box;
  overflow: auto;
}

#map {
  flex-basis: 0;
  flex-grow: 4;
  height: 100%;
}

HTML

<!DOCTYPE html>
<html>
  <head>
    <title>Data Layer: Drag and Drop GeoJSON</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <link
      href="https://unpkg.com/material-components-web@6.0.0/dist/material-components-web.css"
      rel="stylesheet"
    />
    <link
      rel="stylesheet"
      href="https://fonts.googleapis.com/icon?family=Material+Icons"
    />

    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script src="./index.js"></script>
  </head>
  <body>
    <div id="container">
      <div id="map"></div>
      <div id="sidebar" class="mdc-typography">
        <div class="file" draggable="true" data-value="0">
          <span class="material-icons">text_snippet</span>
          <div class="filename">polygons.geojson</div>
        </div>
        <div class="file" draggable="true" data-value="1">
          <span class="material-icons">text_snippet</span>
          <div class="filename">points.geojson</div>
        </div>
        <div class="file" draggable="true" data-value="2">
          <span class="material-icons">text_snippet</span>
          <div class="filename">polyline.geojson</div>
        </div>
      </div>
    </div>

    <!-- Async script executes immediately and must be after any DOM elements used in callback. -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initialize&v=weekly"
      async
    ></script>
  </body>
</html>
let map; function initMap() { // set up the map map = new google.maps.Map(document.getElementById("map"), { center: new google.maps.LatLng(0, 0), zoom: 4, }); } function loadGeoJsonString(geoString) { try { const geojson = JSON.parse(geoString); map.data.addGeoJson(geojson); } catch (e) { alert("Not a GeoJSON file!"); } zoom(map); } /** * Update a map's viewport to fit each geometry in a dataset */ function zoom(map) { const bounds = new google.maps.LatLngBounds(); map.data.forEach((feature) => { const geometry = feature.getGeometry(); if (geometry) { processPoints(geometry, bounds.extend, bounds); } }); map.fitBounds(bounds); } /** * Process each point in a Geometry, regardless of how deep the points may lie. */ function processPoints(geometry, callback, thisArg) { if (geometry instanceof google.maps.LatLng) { callback.call(thisArg, geometry); } else if (geometry instanceof google.maps.Data.Point) { callback.call(thisArg, geometry.get()); } else { geometry.getArray().forEach((g) => { processPoints(g, callback, thisArg); }); } } /* DOM (drag/drop) functions */ function initEvents() { [...document.getElementsByClassName("file")].forEach((fileElement) => { fileElement.addEventListener( "dragstart", (e) => { e.dataTransfer.setData( "text/plain", JSON.stringify(files[Number(e.target.dataset.value)]) ); console.log(e); }, false ); }); // set up the drag & drop events const mapContainer = document.getElementById("map"); mapContainer.addEventListener("dragenter", addClassToDropTarget, false); mapContainer.addEventListener("dragover", addClassToDropTarget, false); mapContainer.addEventListener("drop", handleDrop, false); mapContainer.addEventListener("dragleave", removeClassFromDropTarget, false); } function addClassToDropTarget(e) { e.stopPropagation(); e.preventDefault(); document.getElementById("map").classList.add("over"); return false; } function removeClassFromDropTarget(e) { document.getElementById("map").classList.remove("over"); } function handleDrop(e) { e.preventDefault(); e.stopPropagation(); removeClassFromDropTarget(e); const files = e.dataTransfer.files; if (files.length) { // process file(s) being dropped // grab the file data from each file for (let i = 0, file; (file = files[i]); i++) { const reader = new FileReader(); reader.onload = function (e) { loadGeoJsonString(reader.result); }; reader.onerror = function (e) { console.error("reading failed"); }; reader.readAsText(file); } } else { // process non-file (e.g. text or html) content being dropped // grab the plain text version of the data const plainText = e.dataTransfer.getData("text/plain"); console.log(plainText); if (plainText) { loadGeoJsonString(plainText); } } // prevent drag event from bubbling further return false; } function initialize() { initMap(); initEvents(); } const files = [ { type: "FeatureCollection", features: [ { type: "Feature", properties: {}, geometry: { type: "Polygon", coordinates: [ [ [-99.49218749999999, -11.867350911459294], [24.960937499999996, -11.867350911459294], [24.960937499999996, 47.517200697839414], [-99.49218749999999, 47.517200697839414], [-99.49218749999999, -11.867350911459294], ], ], }, }, ], }, { type: "FeatureCollection", features: [ { type: "Feature", properties: {}, geometry: { type: "Point", coordinates: [81.2109375, 50.064191736659104], }, }, { type: "Feature", properties: {}, geometry: { type: "Point", coordinates: [103.35937499999999, -47.98992166741417], }, }, { type: "Feature", properties: {}, geometry: { type: "Point", coordinates: [-46.05468749999999, 64.01449619484472], }, }, { type: "Feature", properties: {}, geometry: { type: "Point", coordinates: [-113.203125, 37.996162679728116], }, }, { type: "Feature", properties: {}, geometry: { type: "Point", coordinates: [-73.828125, -32.249974455863295], }, }, ], }, { type: "FeatureCollection", features: [ { type: "Feature", properties: {}, geometry: { type: "LineString", coordinates: [ [147.65625, -5.266007882805485], [118.47656249999999, 43.83452678223682], [80.85937499999999, -30.145127183376115], [35.15625, 51.83577752045248], [-15.468749999999998, -23.563987128451217], [-29.53125, 44.33956524809713], [-73.47656249999999, -32.842673631954305], [-104.765625, 35.460669951495305], ], }, }, ], }, ];
html { height: 100%; } body { height: 100%; margin: 0; padding: 0; overflow: hidden; } #map { height: 100%; } #map.over { opacity: 0.5; background-color: rgba(100, 100, 100, 0.5); } #sidebar { flex-direction: column; align-items: center; justify-content: center; overflow: auto; } .file { display: flex; flex-flow: column; margin-top: 1em; cursor: move; text-align: center; } .file:hover .material-icons { color: darkorange; } .file:hover .filename { font-weight: bold; } .file .material-icons { font-size: 50px; color: orange; } .file .material-icons:hover { color: darkorange; } .file .filename { margin-top: 0.5em; font-size: 20px; color: #333333; } /* Optional: Makes the sample page fill the window. */ html, body { height: 100%; margin: 0; padding: 0; } #container { height: 100%; display: flex; } #sidebar { flex-basis: 15rem; flex-grow: 1; padding: 1rem; max-width: 30rem; height: 100%; box-sizing: border-box; overflow: auto; } #map { flex-basis: 0; flex-grow: 4; height: 100%; }
<!DOCTYPE html> <html> <head> <title>Data Layer: Drag and Drop GeoJSON</title> <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script> <link href="https://unpkg.com/material-components-web@6.0.0/dist/material-components-web.css" rel="stylesheet" /> <link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons" /> <!-- jsFiddle will insert css and js --> </head> <body> <div id="container"> <div id="map"></div> <div id="sidebar" class="mdc-typography"> <div class="file" draggable="true" data-value="0"> <span class="material-icons">text_snippet</span> <div class="filename">polygons.geojson</div> </div> <div class="file" draggable="true" data-value="1"> <span class="material-icons">text_snippet</span> <div class="filename">points.geojson</div> </div> <div class="file" draggable="true" data-value="2"> <span class="material-icons">text_snippet</span> <div class="filename">polyline.geojson</div> </div> </div> </div> <!-- Async script executes immediately and must be after any DOM elements used in callback. --> <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB41DRUbKWJHPxaFjMAwdrzWzbVKartNGg&callback=initialize&v=weekly&channel=2" async ></script> </body> </html>

Try Sample

Clone Sample

Git and Node.js are required to run this sample locally. Follow these instructions to install Node.js and NPM. The following commands clone, install dependencies and start the sample application.

  git clone -b sample-layer-data-dragndrop git@github.com:googlemaps/js-samples.git
  cd js-samples
  npm i
  npm start

Other samples can be tried by switching to any branch beginning with sample-SAMPLE_NAME.

  git checkout sample-SAMPLE_NAME
  npm i
  npm start