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 Map
class and to display maps in 3D, use the Scene
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.
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 Web
and Web
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
.
If using ArcGIS Enterprise, the portal URL must be specified.
When the Web
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
const webMap = new WebMap({ // Define the web map reference
portalItem: {
id: "41281c51f9de45edaf1c8ed44bb10e30",
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 Map
and Scene
class.
A Map
displays a 2D view, and a Scene
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.
const mapView = new MapView({ // Create MapView object
map: myMap,
container: "mapViewDiv"
});
Set the visible portion of the map
The initial position for the Map
and Scene
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.
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 go
method of Map
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 go
method can accept a Geometry
, Graphic
, or Viewpoint
object. Additional options can control the animation.
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 hit
method to find features where the user clicked.
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.
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"
});