Introduction to maps (2D)

Maps are containers used to manage references to layers and basemaps. Views are used to display the map layers and handle user interactions, popups, widgets, and the map location.

Working with maps

Maps are created from the Map class. Map objects are always passed to a View object. To display maps in 2D, use the MapView class and to display maps in 3D, use the SceneView class.

See Scenes (3D) in this guide for more information about working in 3D.

Create a new map

One way to create a map is to make a new instance of the Map class while specifying a basemap and optionally a collection of layers.

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const myMap = new Map({                // Create a Map object
  basemap: "streets-vector",
  layers: additionalLayers             // Optionally, add additional layers collection
});

const mapView = new MapView({          // The View for the Map object
  map: myMap,
  container: "mapDiv"
});

Create a map from a web map

The second way to create a map is to load a web map (for 2D maps) or a web scene (for 3D maps).

Web maps and web scenes are JSON structures that contain settings for a map or a scene. This includes settings for the basemap, layers, layer styling, popups, legends, labels, and more. They are typically created interactively with the ArcGIS Online map viewer or the ArcGIS Online scene viewer. ArcGIS Online or ArcGIS Enterprise assigns them a unique ID and stores them as portal items.

The WebMap and WebScene classes can be used to access and load web maps and web scenes by their unique ID. An item's ID can be identified in the URL in the map viewer and scene viewer or in the item page. The default portal is ArcGIS Online and the URL is https://www.arcgis.com. If using ArcGIS Enterprise, the portal URL must be specified.

When the WebMap object load a web map, all of the settings are automatically applied to the Map. For example, the basemap and layers are set, the layer styles are applied, and the popups are defined for each layer.

Create a map from a WebMap

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const webMap = new WebMap({                        // Define the web map reference
  portalItem: {
    id: "237b9584339446a0b56317b5962a4971",
    portal: "https://www.arcgis.com"               // Default: The ArcGIS Online Portal
  }
});

const view = new MapView({
  map: webMap,                                     // Load the web map
  container: "viewDiv"
});

Working with Views

The primary role of the view is to display layers, popups, and UI widgets, handle user interactions, and to specify which portion of the world the map should be focused on (i.e. the "extent" of the map).

Create a view

There are separate classes for creating views for maps and scenes: a MapView and SceneView class. A MapView displays a 2D view, and a SceneView displays a 3D view, of a Map object.

For a map to be visible, a view object requires a Map object and a String identifying the id attribute of a div element or a div element reference.

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const mapView = new MapView({          // Create MapView object
  map: myMap,
  container: "mapViewDiv"
});

Set the visible portion of the map

The initial position for the MapView and SceneView can be set by setting the center and the zoom or scale properties when the view is created. The view position can also be updated after it is initialized by updating the properties programmatically.

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const view = new MapView({
  center: [ -112, 38 ],         // The center of the map as lon/lat
  zoom: 13                      // Sets the zoom level of detail (LOD) to 13
});

Learn how to create 2D views in the Display a map tutorial.

Animate the view to a new position

The goTo method of MapView also changes the location of the view but provides the additional option to transition smoothly. This technique is often used to "fly" from one location to another on the surface or to zoom to results of a search.

The goTo method can accept a Geometry, Graphic, or Viewpoint object. Additional options can control the animation.

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view.goTo(                           // go to point with a custom animation duration
  { center: [-114, 39] },
  { duration: 5000 }
);

Interacting with the view

The view is also responsible for handling user interaction and displaying popups. The view provides multiple event handlers for user interactions such as mouse clicks, keyboard input, touch screen interactions, joysticks, and other input devices.

When a user clicks on the map, the default behavior is to show any popups that have been pre-configured in your layers. This behavior can also be approximated manually with the following code by listening for the click event and using the hitTest() method to find features where the user clicked.

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view.popupEnabled = false;  // Disable the default popup behavior

view.on("click", function(event) { // Listen for the click event
  view.hitTest(event).then(function (hitTestResults){ // Search for features where the user clicked
    if(hitTestResults.results) {
      view.openPopup({ // open a popup to show some of the results
        location: event.mapPoint,
        title: "Hit Test Results",
        content: hitTestResults.results.length + "Features Found"
      });
    }
  })
});

Adding widgets and UI components to the view

The view is also a container for overlaying widgets and HTML Elements. The view.ui provides a DefaultUI container that is used to display the default widgets for the view. Additional widgets and HTML Elements can also be added to the view by using the view.ui.add method. The code snippet below demonstrates adding widgets that allows users to search for an address or place.

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  var searchWidget = new Search({
    view: view
  });

  // Add the search widget to the top right corner of the view
  view.ui.add(searchWidget, {
    position: "top-right"
  });