Add a feature layer as GeoJSON | OpenLayers

Learn how to add featuresA feature is a single record, also known as a row, that represents a real-world entity. It typically contains a geometry (point, multipoint, polyline, or polygon) and attributes but it can also contain just attributes.Learn more from feature layersA feature layer (client-side) is a data layer that can access and display features from a feature service that has the same type of geometry and attribute fields.Learn more to a mapA map is a collection of layers that are displayed in 2D. It is typically composed of a basemap layer and data layers.Learn more.

Add a feature layer as GeoJSON using API key authentication

A feature layerA feature layer (client-side) is a data layer that can access and display features from a feature service that has the same type of geometry and attribute fields.Learn more is a dataset in a hosted feature serviceA feature service is a data service that provides access to spatial and non-spatial data in feature layers, feature layer views, and tables.Learn more. Each feature layer contains featuresA feature is a single record, also known as a row, that represents a real-world entity. It typically contains a geometry (point, multipoint, polyline, or polygon) and attributes but it can also contain just attributes.Learn more with a single geometryA geometry is a geometric shape, such as a point, polyline, or polygon, that contains one or more coordinates and a spatial reference.Learn more type (point, line, or polygon), and a set of attributesAttributes are fields and values for a single feature or non-spatial record. They are typically stored in a database or service such as a feature service.Learn more. You can access and display features by making query requests to the feature service and displaying them in a map.

In this tutorial, you access and display three different hosted feature layersA feature layer (server-side) is a spatially-enabled table in a feature service. All features in a feature layer share the same geometry type and set of fields.Learn more. The data is accessed and displayed as GeoJSON.

The feature layers are:

Prerequisites

You need an ArcGIS Location Platform or ArcGIS Online account.

Steps

Get the starter app

Select a type of authentication and follow the steps to create a new app.

Choose API key authentication if you:

Want the easiest way to get started.
Want to build public applicationsA public application is an application that allows anonymous access without requiring users to sign in with an ArcGIS account. It supports API key or app authentication.Learn more that access ArcGIS Location ServicesArcGIS Location Services, also referred to as Location Services, are services hosted by Esri that provide geospatial functionality for developing mapping applications. They include the ArcGIS Basemap Styles service, ArcGIS Static Basemap Tiles service, ArcGIS Places service, ArcGIS Geocoding service, ArcGIS Routing service, ArcGIS GeoEnrichment service, and ArcGIS Elevation service. An ArcGIS Location Platform or ArcGIS Online account is required to use the services.Learn more and secure itemsAn item, also known as a content item, is a resource stored in a portal such as a web map, hosted layer, style, script tool, file, or notebook.Learn more.
Have an ArcGIS Location Platform or ArcGIS Online account.

Choose user authentication if you:

Want to build private applications.
Require application users to sign in with their own ArcGIS accountAn ArcGIS account is an identity with a user type and set of privileges that can access specific ArcGIS products, tools, APIs, services, and resources. The main account types that can be used for development are an ArcGIS Location Platform account, ArcGIS Online account, and ArcGIS Enterprise account. ArcGIS Location Platform and ArcGIS Online accounts are also associated with a subscription.Learn more and access resources their behalf.
Have an ArcGIS Online account.

To learn more about both types of authentication, go to Authentication.

You can choose one of the following to create a new CodePen:

Option 1: Complete the Display a map tutorial; or,
Option 2: Start from the Display a map tutorial .

Set up authentication

Create a new API key credentialAPI key credentials are an item that contains the parameters used to create and manage long-lived access tokens for API key authentication. They are a type of developer credential.Learn more with the correct privileges to get an access token.

Go to the Create an API key tutorial and create an API keyAn API key is a long-lived access token created using API key credentials. They are valid for up to one year and are typically embedded directly into client applications.Learn more with the following privilege(s)Privileges are a set of permissions assigned to ArcGIS accounts, developer credentials, and applications that grant access to secure resources and functionality in ArcGIS.Learn more:
- Privileges
  - Location services > Basemaps
- Item access
  - Note: If you are using your own custom data layer for this tutorial, you need to grant the API key credentialsAPI key credentials are an item that contains the parameters used to create and manage long-lived access tokens for API key authentication. They are a type of developer credential.Learn more access to the layer item. Learn more in Item access privileges.

Create a new OAuth credentialOAuth credentials are an item that contains parameters required to implement user authentication or app authentication, including a client_id, client_secret, and redirect URIs. They are a type of developer credential.Learn more to register the application.

Go to the Create OAuth credentials for user authentication tutorial to create an OAuth credential.
Copy the Client ID and Redirect URL from your OAuth credentials item and paste them to a safe location. They will be used in a later step.

Set developer credentials

Use the API key or OAuth developer credentialsDeveloper credentials are a type of item in a portal that contains parameters for authentication. There are two types of developer credentials: API key credentials and OAuth credentials.Learn more so your application can access ArcGIS servicesA service, also known as an ArcGIS service, is software that supports an ArcGIS REST API and provides geospatial functionality or data. A service can be hosted by Esri or in ArcGIS Enterprise.Learn more.

Update the accessToken variable to use your API key.

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    /* Use for API key authentication */
    const accessToken = "YOUR_ACCESS_TOKEN";
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In both the index.html and callback.html files, replace YOUR_CLIENT_ID and YOUR_REDIRECT_URL with the client ID and redirect URL of your OAuth credentialsOAuth credentials are an item that contains parameters required to implement user authentication or app authentication, including a client_id, client_secret, and redirect URIs. They are a type of developer credential.Learn more.

index.html
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    /* Use for user authentication */
    const clientId = "YOUR_CLIENT_ID"; // Your client ID from OAuth credentials
    const redirectUri = ""YOUR_REDIRECT_URI""; // The redirect URL registered in your OAuth credentials
    const session = await arcgisRest.ArcGISIdentityManager.beginOAuth2({
      clientId,
      redirectUri,
      portal: "https://www.arcgis.com/sharing/rest" // Your portal URL
    });

    const accessToken = session.token;

callback.html
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    arcgisRest.ArcGISIdentityManager.completeOAuth2({
      clientId: "YOUR_CLIENT_ID", // Your client ID from OAuth credentials
      redirectUri: "YOUR_REDIRECT_URI", // The redirect URL registered in your OAuth credentials
      portal: "https://www.arcgis.com/sharing/rest" // Your portal URL
    });

Run the app and ensure you can sign in successfully.

If you are unable to sign in, make sure you have the correct redirect URL and port. This URL varies based on your application and typically takes the format of https://<server>[:port]/callback.html or http://my-arcgis-app:/auth. For example, if you are running an application on http://127.0.0.1:5500/, set http://127.0.0.1:5500/callback.html as your redirect URL in the index.html and callback.html file and your developer credential. They all have to match!

Add references to ArcGIS REST JS

This tutorial uses ArcGIS REST JS for accessing the feature service. It also uses the ol-popup library to display pop-ups.

In the <head> element, add references to the ArcGIS REST JS and ol-popup libraries.

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    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@v10.9.0/ol.css">
    <script src="https://cdn.jsdelivr.net/npm/ol@v10.9.0/dist/ol.js"></script>

    <script src="https://cdn.jsdelivr.net/npm/ol-mapbox-style@13.4.1/dist/olms.js"></script>

    <script src="https://unpkg.com/@esri/arcgis-rest-request@4/dist/bundled/request.umd.js"></script>
    <script src="https://unpkg.com/ol-popup@5.1.1/dist/ol-popup.js"></script>
    <link rel="stylesheet" href="https://unpkg.com/ol-popup@5.1.1/src/ol-popup.css">
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Add a point feature layer

The trailheads feature layerA feature layer (server-side) is a spatially-enabled table in a feature service. All features in a feature layer share the same geometry type and set of fields.Learn more contains feature with a pointA point is a type of geometry containing a single set of x,y coordinates and a spatial reference.Learn more geometry. Use a Vector layer to access the feature layer by URL and display the points. By default, they will display as white circles with blue outlines.

Create a VectorSource. Pass a new GeoJSON as the format parameter. For the url parameter, pass a direct link to a FeatureServer endpoint.

The URL contains an f=geojson parameter to request data in GeoJSON format. For more information about querying a Feature ServiceA feature service is a data service that provides access to spatial and non-spatial data in feature layers, feature layer views, and tables.Learn more, see the Query a feature layer (SQL) and Query a feature layer (spatial) tutorials.

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    const basemapId = "arcgis/streets";
    const basemapURL = `https://basemapstyles-api.arcgis.com/arcgis/rest/services/styles/v2/styles/${basemapId}?token=${accessToken}`;

    olms.apply(map, basemapURL).then(function (map) {

      const pointLayerName = "Trailheads";
      const pointLayerURL =
        "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +
        pointLayerName +
        "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";

      const pointSource = new ol.source.Vector({
        format: new ol.format.GeoJSON(),
        url: pointLayerURL,

      });
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Add the data attributionData attribution is the requirement to display the names of data source providers in all applications when accessing ArcGIS content, layers, or services.Learn more for the feature layer source.

Go to the Trailheads (Santa Monica Mountains) itemAn item, also known as a content item, is a resource stored in a portal such as a web map, hosted layer, style, script tool, file, or notebook.Learn more.
Scroll down to the Acknowledgments section and copy its value.

Paste the copied value to the attributions property.

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    const basemapId = "arcgis/streets";
    const basemapURL = `https://basemapstyles-api.arcgis.com/arcgis/rest/services/styles/v2/styles/${basemapId}?token=${accessToken}`;

    olms.apply(map, basemapURL).then(function (map) {

      const pointLayerName = "Trailheads";
      const pointLayerURL =
        "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +
        pointLayerName +
        "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";

      const pointSource = new ol.source.Vector({
        format: new ol.format.GeoJSON(),
        url: pointLayerURL,

        // Attribution text retrieved from https://arcgis.com/home/item.html?id=883cedb8c9fe4524b64d47666ed234a7
        attributions: ["Los Angeles GeoHub |"]

      });
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Create a Vector layer using the Vector source you defined.

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      const pointSource = new ol.source.Vector({
        format: new ol.format.GeoJSON(),
        url: pointLayerURL,

        // Attribution text retrieved from https://arcgis.com/home/item.html?id=883cedb8c9fe4524b64d47666ed234a7
        attributions: ["Los Angeles GeoHub |"]

      });

      const pointLayer = new ol.layer.Vector({
        source: pointSource
      });
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Add a line feature layer

The Trails feature layerA feature layer (server-side) is a spatially-enabled table in a feature service. All features in a feature layer share the same geometry type and set of fields.Learn more contains features with a line geometryA geometry is a geometric shape, such as a point, polyline, or polygon, that contains one or more coordinates and a spatial reference.Learn more. Use a Vector layer to access the feature layer by URL and display the lines. By default, the features are displayed as blue lines.

Create a VectorSource with format and url parameters.

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      const pointLayer = new ol.layer.Vector({
        source: pointSource
      });

      const lineLayerName = "Trails";
      const lineLayerURL =
        "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +
        lineLayerName +
        "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";

      const lineSource = new ol.source.Vector({
        format: new ol.format.GeoJSON(),
        url: lineLayerURL,

      });
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Go to the Trails itemAn item, also known as a content item, is a resource stored in a portal such as a web map, hosted layer, style, script tool, file, or notebook.Learn more.
Scroll down to the Acknowledgments section and copy its value.

Paste the copied value to the attributions property.

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      const pointLayer = new ol.layer.Vector({
        source: pointSource
      });

      const lineLayerName = "Trails";
      const lineLayerURL =
        "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +
        lineLayerName +
        "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";

      const lineSource = new ol.source.Vector({
        format: new ol.format.GeoJSON(),
        url: lineLayerURL,

        // Attribution text retrieved from https://arcgis.com/home/item.html?id=69e12682738e467eb509d8b54dc73cbd
        attributions: ["Los Angeles GeoHub |"]

      });
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Create a Vector layer using the Vector source you defined.

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      const lineSource = new ol.source.Vector({
        format: new ol.format.GeoJSON(),
        url: lineLayerURL,

        // Attribution text retrieved from https://arcgis.com/home/item.html?id=69e12682738e467eb509d8b54dc73cbd
        attributions: ["Los Angeles GeoHub |"]

      });

      const lineLayer = new ol.layer.Vector({
        source: lineSource
      });
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Add a polygon feature layer

The Parks and Open Space feature layerA feature layer (server-side) is a spatially-enabled table in a feature service. All features in a feature layer share the same geometry type and set of fields.Learn more contains features with a polygonA polygon is a type of geometry containing an array of rings and a spatial reference. Each ring contains an array of point coordinates, where the first and last point are the same.Learn more geometryA geometry is a geometric shape, such as a point, polyline, or polygon, that contains one or more coordinates and a spatial reference.Learn more. Use a Vector layer to access the feature layer by URL and display the polygons. By default, polygon features are displayed as translucent white fill with blue outlines.

Create a VectorSource with format and url parameters.

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      const lineLayer = new ol.layer.Vector({
        source: lineSource
      });

      const polygonLayerName = "Parks_and_Open_Space";
      const polygonLayerURL =
        "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +
        polygonLayerName +
        "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";

      const polygonSource = new ol.source.Vector({
        format: new ol.format.GeoJSON(),
        url: polygonLayerURL,

      });
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Go to the Parks and Open Space itemAn item, also known as a content item, is a resource stored in a portal such as a web map, hosted layer, style, script tool, file, or notebook.Learn more.
Scroll down to the Acknowledgments section and copy its value.

Paste the copied value to the attributions property.

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      const lineLayer = new ol.layer.Vector({
        source: lineSource
      });

      const polygonLayerName = "Parks_and_Open_Space";
      const polygonLayerURL =
        "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/" +
        polygonLayerName +
        "/FeatureServer/0/query?where=1%3D1&outFields=*&returnGeometry=true&f=geojson";

      const polygonSource = new ol.source.Vector({
        format: new ol.format.GeoJSON(),
        url: polygonLayerURL,

        // Attribution text retrieved from https://arcgis.com/home/item.html?id=f2ea5d874dad427294641d2d45097c0e
        attributions: ["Los Angeles GeoHub |"]

      });
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Create a Vector layer using the Vector source you defined.

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      const polygonSource = new ol.source.Vector({
        format: new ol.format.GeoJSON(),
        url: polygonLayerURL,

        // Attribution text retrieved from https://arcgis.com/home/item.html?id=f2ea5d874dad427294641d2d45097c0e
        attributions: ["Los Angeles GeoHub |"]

      });

      const polygonLayer = new ol.layer.Vector({
        source: polygonSource
      });
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To display multiple layers in a specific order, you group them using a LayerGroup. Add all of the layers you created to the group, then display it on the map using map.addLayer().

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      const layerGroup = new ol.layer.Group({
        layers: [polygonLayer, lineLayer, pointLayer]
      });

      map.addLayer(layerGroup);
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Add a pop-up

You can use a Popup to show data attributes for a feature when you click on them. A popup is a type of Overlay so you add it to the map with map.addOverlay. To get a feature, you use the click event and map.getFeaturesAtPixel to get the features at a click point. You also use the point to position the Popup at the correct location.

For a full list of possible attributes to show, see the feature layerA feature layer (server-side) is a spatially-enabled table in a feature service. All features in a feature layer share the same geometry type and set of fields.Learn more pages:

Create a Popup and save it to a popup variable. Add it to the map with map.addOverlay.

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      const polygonLayer = new ol.layer.Vector({
        source: polygonSource
      });

      const layerGroup = new ol.layer.Group({
        layers: [polygonLayer, lineLayer, pointLayer]
      });

      map.addLayer(layerGroup);

      const popup = new Popup();
      map.addOverlay(popup);
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Add a click event handler. Inside, check if a feature from the trailheads layer was clicked. If so, move the pop-up, and show the trailhead name and park name (TRL_NAME and PARK_NAME). Otherwise, check the trails layer; show the trail name, length and elevation gain (TRL_NAME, LENGTH_MI, ELEV_GAIN) if it was clicked. Otherwise, check the parks layer; show the park name and managing agency (PARK_NAME and MNG_AGENCY) if it was clicked. Otherwise, hide the pop-up with popup.hide;

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      const popup = new Popup();
      map.addOverlay(popup);

      map.on("click", (event) => {
        let feature = map.getFeaturesAtPixel(event.pixel, {
          layerFilter: (l) => l === pointLayer
        })[0];
        if (feature) {
          popup.show(event.coordinate, `<strong>${feature.get("TRL_NAME")}</strong><br/>${feature.get("PARK_NAME")}`);
          return;
        }

        feature = map.getFeaturesAtPixel(event.pixel, {
          layerFilter: (l) => l === lineLayer
        })[0];
        if (feature) {
          popup.show(
            event.coordinate,
            `<strong>${feature.get("TRL_NAME")}</strong><br/>${feature.get("LENGTH_MI")} miles, ${feature.get("ELEV_GAIN")} feet elevation gain.`
          );
          return;
        }

        feature = map.getFeaturesAtPixel(event.pixel, {
          layerFilter: (l) => l === polygonLayer
        })[0];
        if (feature) {
          popup.show(event.coordinate, `<strong>${feature.get("PARK_NAME")}</strong><br/>${feature.get("MNG_AGENCY")}`);
          return;
        }
        popup.hide();
      });
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Run the app

Run the app.

You should now be able to click on features to see information in a pop-up.

What's next?

Learn how to use additional location services in these tutorials: