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Geolocation coordinates to Point geometry to use in buffer

Question asked by teske12 on Dec 2, 2016
Latest reply on Dec 3, 2016 by teske12

I am a bit new to JavaScript. I want to buffer the location of a person's position when they click the Locate Button Widget.

 

I modified the Locate Widget in the JavaScript API 4.0 a little bit. I am trying to get the coordinates of the position when you click the button, so that I can create a point geometry to use in a buffer. I have looked around and can't find a firm answer. I saw that you need to use the getCurrentPosition function, but some reason I can't properly implement it in my code. This is what I have so far:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
  <title>Final Project</title>
 
  <link rel="stylesheet" href="https://js.arcgis.com/4.1/esri/css/main.css">
  <script src="https://js.arcgis.com/4.1/"></script>

  <style>
    html,
    body,
    #viewDiv {
      padding: 0;
      margin: 0;
      height: 100%;
      width: 100%;
    }
   
    #legendDiv {
      max-width: 300px;
      background-color: black;
      padding: 8px;
      color: white;
      opacity: 0.85;
    }

    p {
      max-width: 400px;
      background-color: black;
      padding: 15px;
      border: 1px solid white;
      color: white;
      opacity: 0.95;
    }
   
    #toggle {
      bottom: 20px;
      left: 20px;
      position: absolute;
      z-index: 99;
      max-width: 105px;
      background-color: black;
      border-radius: 8px;
      padding: 10px;
      color: white;
      opacity: 0.85;
    }

    .esri-locate {
      font-size: 18px;
      background-color: white;
      color: red;
      width: 120px;
      height: 40px;
      padding: 0;
      margin: 0;
      border-radius: 8px;
      overflow: hidden;
      cursor: pointer;
}
    .esri-locate span {
      display: none;
    }
   
    .esri-locate:after {
      content: 'GeoProcess';
    }

   
  </style>



  <script>
    require([
      "esri/Map",
      "esri/layers/FeatureLayer",
      "esri/views/MapView",
      "esri/widgets/Legend",
      "esri/config",
      "esri/core/urlUtils",
      "esri/widgets/Locate",
      "esri/layers/GraphicsLayer",
      "esri/Graphic",
      "esri/symbols/SimpleFillSymbol",
      "esri/geometry/geometryEngine",
      "dojo/dom-construct",
      "dojo/dom",
      "dojo/on",
      "dojo/domReady!"
    ], function(
      Map,
      FeatureLayer,
      MapView,
      Legend,
      esriConfig,
      urlUtils,
      Locate,
      GraphicsLayer,
      Graphic,
      SimpleFillSymbol,
      geometryEngine,
      domConstruct,
      dom,
      on) {
     
      var floodLayer = new FeatureLayer({
        url: "https://igems.doi.gov/arcgis/rest/services/igems_haz/MapServer/0",
        visible: true
      });      

      var volcanoeLayer = new FeatureLayer({
          url: "https://igems.doi.gov/arcgis/rest/services/igems_haz/MapServer/1",
          visible: true
        });   
     
      var earthquakeLayer = new FeatureLayer({
          url: "https://igems.doi.gov/arcgis/rest/services/igems_haz/MapServer/3",
          visible: true
        });   
     
      var hurricaneLayer = new FeatureLayer({
          url: "https://igems.doi.gov/arcgis/rest/services/igems_haz/MapServer/5",
          visible: true
        });  
     
      var wildfireLayer = new FeatureLayer({
          url: "https://igems.doi.gov/arcgis/rest/services/igems_haz/MapServer/10",
          visible: true
        });
     
      var shelterLayer = new FeatureLayer({
          url: "http://gis.fema.gov/REST/services/NSS/FEMA_NSS/MapServer/5",
          visible: false
        });
     
      var gLayer = new GraphicsLayer({});
     
      var map = new Map({
        basemap: "dark-gray",
        layers: [gLayer, shelterLayer, floodLayer, volcanoeLayer, earthquakeLayer, hurricaneLayer, wildfireLayer]
      });

      var view = new MapView({
        container: "viewDiv",
        center: [-96.050173, 39.216911],
        zoom: 5,
        map: map
      });
     
      var legend = new Legend({
          view: view,
          layerInfos: [{
              layer: floodLayer,
              title: "Floods"
            },
            {
                 layer: volcanoeLayer,
                 title: "Volcanoes"
            },
            {
                 layer: earthquakeLayer,
                 title: "Earthquakes"
            },
            {
                 layer: hurricaneLayer,
                 title: "Hurricanes"
            },
            {
                 layer: wildfireLayer,
                 title: "Wildfires"
            }]
        }, "legendDiv");
     
      view.ui.add(legend, "bottom-right");
     
      var info = domConstruct.create("infoDiv", {
        innerHTML: "<p>This map presents the geospatial locations for current natural hazards events (such as earthquakes, hurricanes, floods, and wildfires) as well as the locations of FEMA shelters. <br> <br> By clicking the button, this application will geocode your location, create a 5-10 mile buffer around that location, and provide directions to the closest shelter.</p>",
      });
     
      view.ui.add(info, "top-right");
     
      var shelterTog = dom.byId("shelterToggle");
      var wildfireTog = dom.byId("wildfireToggle");
      var hurricaneTog = dom.byId("hurricaneToggle");
      var earthquakeTog = dom.byId("earthquakeToggle");
      var volcanoeTog = dom.byId("volcanoeToggle");
      var floodTog = dom.byId("floodToggle");
     
      on(shelterTog, "change", function(){
           shelterLayer.visible = shelterTog.checked;
      });
     
      on(wildfireTog, "change", function(){
              wildfireLayer.visible = wildfireTog.checked;
      });
     
      on(hurricaneTog, "change", function(){
              hurricaneLayer.visible = hurricaneTog.checked;
      });

      on(earthquakeTog, "change", function(){
              earthquakeLayer.visible = earthquakeTog.checked;
      });
     
      on(volcanoeTog, "change", function(){
              volcanoeLayer.visible = volcanoeTog.checked;
      });
     
      on(floodTog, "change", function(){
              floodLayer.visible = floodTog.checked;
      });
    
      //Locate Position
      var locateBtn = new Locate({
           view: view,
      });
      locateBtn.startup();
     
      view.ui.add(locateBtn, {
           position: "top-left",
           index: 0
      });
     
      //Creat a symbol for buffer
      var fillSymbol = new SimpleFillSymbol({
        color: [227, 139, 79, 0.8],
        outline: {color: [255, 255, 255],
          width: 1
        }
      });
     
      //Begin geoprocessing
      locateBtn.on("locate", function(geoProcess){
          view.zoom = 15;
         
          navigator.geolocation.getCurrentPosition(function(position) {
              var pt = new Point ({
                   longitude: position.coords.longitude,
                   latitude: position.coords.latitude
              });
             
              var buffer = geometryEngine.buffer(pt, 100, "miles");
             
              var bufferGraphic = new Graphic({
                geometry: buffer,
                symbol: fillSymbol
              });
             
              gLayer.add(bufferGraphic);
             
            });
      });
    });
  </script>
</head>

<body>
  <div id="viewDiv"></div>
  <div id="legendDiv"></div>
  <span id="toggle">
       <input type="checkbox" id="shelterToggle"> Shelters<br>
       <input type="checkbox" id="wildfireToggle" checked> Wildfires<br>
       <input type="checkbox" id="hurricaneToggle" checked> Hurricanes<br>
       <input type="checkbox" id="earthquakeToggle" checked> Earthquakes<br>
       <input type="checkbox" id="volcanoeToggle" checked> Volcanoes<br>
       <input type="checkbox" id="floodToggle" checked> Floods
  </span>
</body>

</html>

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