GeoRSSLayer | API Reference | ArcGIS Maps SDK for JavaScript 4.31

The GeoRSSLayer class is used to create a layer based on GeoRSS. GeoRSS is a way to add geographic information to an RSS feed. The GeoRSSLayer supports both GeoRSS-Simple and GeoRSS GML encodings, and multiple geometry types.

It exports custom RSS tags as additional attribute fields in the form of simple strings or an array of JSON objects.

The GeoRSSLayer uses a utility service from ArcGIS.com. Therefore a GeoRSS file must be publicly accessible on the internet. If the GeoRSS files are behind the firewall you must to set the esriConfig.geoRSSServiceUrl to your own utility service (requires ArcGIS Enterprise).

Known Limitations

Currently the GeoRSSLayer is not supported in SceneView.

See also

Add a GeoRSSLayer to your Map

Constructors

GeoRSSLayer Constructor new GeoRSSLayer(properties)

Parameter

properties Object

optional

See the properties for a list of all the properties that may be passed into the constructor.

Example

// Typical usage
esriConfig.geoRSSServiceUrl = "https://utility.arcgis.com/sharing/rss";

const layer = new GeoRSSLayer({
  url: "https://disasterscharter.org/charter-portlets/cpi-mvc/activations/feed/rss/"
});

Property Overview

Any properties can be set, retrieved or listened to. See the Watch for changes topic.

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Type	Summary	Class
String	Blend modes are used to blend layers together to create an interesting effect in a layer, or even to produce what seems like a new layer.	GeoRSSLayer
String	The name of the class.	Accessor
Effect\|null\|undefined	Effect provides various filter functions that can be performed on the layer to achieve different visual effects similar to how image filters work.	GeoRSSLayer
String	The unique ID assigned to the layer.	Layer
Boolean	Indicates whether the layer will be included in the legend.	GeoRSSLayer
SimpleLineSymbol	Symbol used to represent line features from the GeoRSS feed.	GeoRSSLayer
String	Indicates how the layer should display in the LayerList widget.	Layer
Error	The Error object returned if an error occurred while loading.	Layer
String	Represents the status of a load operation.	Layer
Object []	A list of warnings which occurred while loading.	Layer
Boolean	Indicates whether the layer's resources have loaded.	Layer
Number	The maximum scale (most zoomed in) at which the layer is visible in the view.	GeoRSSLayer
Number	The minimum scale (most zoomed out) at which the layer is visible in the view.	GeoRSSLayer
Number	The opacity of the layer.	Layer
Map\|Basemap\|Ground\|GroupLayer\|CatalogDynamicGroupLayer\|CatalogLayer	The parent to which the layer belongs.	Layer
Boolean	Enable persistence of the layer in a WebMap or WebScene.	GeoRSSLayer
PictureMarkerSymbol\|SimpleMarkerSymbol	Symbol used to represent point features from the GeoRSS feed.	GeoRSSLayer
SimpleFillSymbol	Symbol used to represent polygon features from the GeoRSS feed.	GeoRSSLayer
Number	Refresh interval of the layer in minutes.	GeoRSSLayer
String	The title of the layer used to identify it in places such as the Legend and LayerList widgets.	GeoRSSLayer
String	For GeoRSSLayer the type is always "geo-rss".	GeoRSSLayer
String	The URL pointing to a GeoRSS file.	GeoRSSLayer
TimeExtent\|null\|undefined	Specifies a fixed time extent during which a layer should be visible.	Layer
Boolean	Indicates if the layer is visible in the View.	Layer

Property Details

blendMode Property blendMode String Since: ArcGIS Maps SDK for JavaScript 4.16 GeoRSSLayer since 4.3, blendMode added at 4.16.

Blend modes are used to blend layers together to create an interesting effect in a layer, or even to produce what seems like a new layer. Unlike the method of using transparency which can result in a washed-out top layer, blend modes can create a variety of very vibrant and intriguing results by blending a layer with the layer(s) below it.

When blending layers, a top layer is a layer that has a blend mode applied. All layers underneath the top layer are background layers. The default blending mode is normal where the top layer is simply displayed over the background layer. While this default behavior is perfectly acceptable, the use of blend modes on layers open up a world of endless possibilities to generate creative maps.

The layers in a GroupLayer are blended together in isolation from the rest of the map.

In the following screenshots, the vintage shaded relief layer is displayed over a firefly world imagery layer. The color blend mode is applied to the vintage shaded relief and the result looks like a new layer.

Known Limitations

The blendMode in 3D SceneViews is supported on BaseTileLayer, ImageryTileLayer, OpenStreetMapLayer, TileLayer, VectorTileLayer, WCSLayer, WebTileLayer, WMTSLayer and GroupLayer.
The blendMode is not supported in the Legend.
See print for known printing limitations.

The following factors will affect the blend result:

Order of all layers
Layer opacity
Opacity of features in layers
Visibility of layers
By default, the very bottom layer in a map is drawn on a transparent background. You can change the MapView's background color.

Blend mode	Description
normal	The top layer is displayed over the background layer. The data of the top layer block the data of background layer where they overlap.
average	Takes the mathematical average of top and background layers. Result of `average` blend mode is often similar to the effect of setting the layer's opacity to 50%.

Lighten blend modes:

The following blend modes create lighter results than all layers. In lighten blend modes, pure black colors in the top layer become transparent allowing the background layer to show through. White in the top layer will stay unchanged. Any color that is lighter than pure black is going to lighten colors in the top layer to varying degrees all way to pure white.

Lighten blend modes can be useful when lightening dark colors of the top layer or removing black colors from the result. The plus, lighten and screen modes can be used to brighten layers that have faded or dark colors on a dark background.

Blend mode	Description
lighten	Compares top and background layers and retains the lighter color. Colors in the top layer become transparent if they are darker than the overlapping colors in the background layer allowing the background layer to show through completely. Can be thought of as the opposite of `darken` blend mode.
lighter	Colors in top and background layers are multiplied by their alphas (layer opacity and layer's data opacity. Then the resulting colors are added together. All overlapping midrange colors are lightened in the top layer. The opacity of layer and layer's data will affect the blend result.
plus	Colors in top and background layers are added together. All overlapping midrange colors are lightened in the top layer. This mode is also known as `add` or `linear-dodge`.
screen	Multiplies inverted colors in top and background layers then inverts the colors again. The resulting colors will be lighter than the original color with less contrast. Screen can produce many different levels of brightening depending on the luminosity values of the top layer. Can be thought of as the opposite of the `multiply` mode.
color-dodge	Divides colors in background layer by the inverted top layer. This lightens the background layer depending on the value of the top layer. The brighter the top layer, the more its color affects the background layer. Decreases the contrast between top and background layers resulting in saturated mid-tones and blown highlights.

Darken blend modes:

The following blend modes create darker results than all layers. In darken blend modes, pure white in the top layer will become transparent allowing the background layer to show through. Black in the top layer will stay unchanged. Any color that is darker than pure white is going to darken a top layer to varying degrees all the way to pure black.

The multiply blend mode is often used to highlight shadows, show contrast, or accentuate an aspect of a map. For example, you can use multiply blend mode on a topographic map displayed over hillshade when you want to have your elevation show through the topographic layer. See the intro to layer blending sample.

The multiply and darken modes can be used to have dark labels of the basemap to show through top layers. See the darken blending sample.

The color-burn mode works well with colorful top and background layers since it increases saturation in mid-tones. It increases the contrast by tinting pixels in overlapping areas in top and bottom layers more towards the top layer color. Use this blend mode, when you want an effect with more contrast than multiply or darken.

The following screenshots show how the multiply blend mode used for creating a physical map of the world that shows both boundaries and elevation. multiply-blend

Blend mode	Description
darken	Emphasizes the darkest parts of overlapping layers. Colors in the top layer become transparent if they are lighter than the overlapping colors in the background layer, allowing the background layer to show through completely.
multiply	Emphasizes the darkest parts of overlapping layers by multiplying colors of the top layer and the background layer. Midrange colors from top and background layers are mixed together more evenly.
color-burn	Intensifies the dark areas in all layers. It increases the contrast between top and background layers, by tinting colors in overlapping area towards the top color. To do this it inverts colors of the background layer, divides the result by colors of the top layer, then inverts the results.

Contrast blend modes:

The following blend modes create contrast by both lightening the lighter areas and darkening the darker areas in the top layer by using lightening or darkening blend modes to create the blend. The contrast blend modes will lighten the colors lighter than 50% gray ([128,128,128]), and darken the colors darker than 50% gray. 50% gray will be transparent in the top layer. Each mode can create a variety of results depending on the colors of top and background layers being blended together. The overlay blend mode makes its calculations based on the brightness of the colors in the background layer while all of the other contrast blend modes make their calculations based on the brightness of the top layer. Some of these modes are designed to simulate the effect of shining a light through the top layer, effectively projecting upon the layers beneath it.

Contrast blend modes can be used to increase the contrast and saturation to have more vibrant colors and give a punch to your layers. For example, you can duplicate a layer and set overlay blend mode on the top layer to increase the contrast and tones of your layer. You can also add a polygon layer with a white fill symbol over a dark imagery layer and apply soft-light blend mode to increase the brightness in the imagery layer.

The following screenshots show an effect of the overlay blend mode on a GraphicsLayer. The left image shows when the buffer graphics layer has the normal blend mode. As you can see, the gray color for the buffer polygon is blocking the intersecting census tracts. The right image shows when the overlay blend mode is applied to the buffer graphics layer. The overlay blend mode darkens or lightens the gray buffer polygon depending on the colors of the background layer while the census tracts layer is shining through. See this in action.

Normal blend mode	Overlay blend mode

Blend mode	Description
overlay	Uses a combination of `multiply` and `screen` modes to darken and lighten colors in the top layer with the background layer always shining through. The result is darker color values in the background layer intensify the top layer, while lighter colors in the background layer wash out overlapping areas in the top layer.
soft-light	Applies a half strength `screen` mode to lighter areas and half strength `multiply` mode to darken areas of the top layer. You can think of the `soft-light` as a softer version of the `overlay` mode.
hard-light	Multiplies or screens the colors, depending on colors of the top layer. The effect is similar to shining a harsh spotlight on the top layer.
vivid-light	Uses a combination of `color-burn` or `color-dodge` by increasing or decreasing the contrast, depending on colors in the top layer.

Component blend modes:

The following blend modes use primary color components, which are hue, saturation and luminosity to blend top and background layers. You can add a feature layer with a simple renderer over any layer and set hue, saturation, color or luminosity blend mode on this layer. With this technique, you create a brand new looking map.

The following screenshots show where the topo layer is blended with world hillshade layer with luminosity blend mode. The result is a drastically different looking map which preserves the brightness of the topo layer while adapting the hue and saturation of the hillshade layer.

Blend mode	Description
hue	Creates an effect with the hue of the top layer and the luminosity and saturation of the background layer.
saturation	Creates an effect with the saturation of the top layer and the hue and luminosity of the background layer. 50% gray with no saturation in the background layer will not produce any change.
luminosity	Creates effect with the luminosity of the top layer and the hue and saturation of the background layer. Can be thought of as the opposite of `color` blend mode.
color	Creates an effect with the hue and saturation of the top layer and the luminosity of the background layer. Can be thought of as the opposite of `luminosity` blend mode.

Composite blend modes:

The following blend modes can be used to mask the contents of top, background or both layers.

Destination modes are used to mask the data of the top layer with the data of the background layer.
Source modes are used to mask the data of the background layer with the data of the top layer.

The destination-in blend mode can be used to show areas of focus such as earthquakes, animal migration, or point-source pollution by revealing the underlying map, providing a bird’s eye view of the phenomenon. Check out multiple blending and groupLayer blending samples to see composite blend modes in action.

The following screenshots show feature and imagery layers on the left side on their own in the order they are drawn in the view. The imagery layer that contains land cover classification rasters. The feature layer contains 2007 county crops data. The right image shows the result of layer blending where destination-in blendMode is set on the imagery layer. As you can see, the effect is very different from the original layers. The blended result shows areas of cultivated crops only (where both imagery and feature layers overlap).

Blend mode	Description
destination-over	Destination/background layer covers the top layer. The top layer is drawn underneath the destination layer. You'll see the top layer peek through wherever the background layer is transparent or has no data.
destination-atop	Destination/background layer is drawn only where it overlaps the top layer. The top layer is drawn underneath the background layer. You'll see the top layer peek through wherever the background layer is transparent or has no data.
destination-in	Destination/background layer is drawn only where it overlaps with the top layer. Everything else is made transparent.
destination-out	Destination/background layer is drawn where it doesn't overlap the top layer. Everything else is made transparent.
source-atop	Source/top layer is drawn only where it overlaps the background layer. You will see the background layer peek through where the source layer is transparent or has no data.
source-in	Source/top layer is drawn only where it overlaps with the background layer. Everything else is made transparent.
source-out	Source/top layer is drawn where it doesn't overlap the background layer. Everything else is made transparent.
xor	Top and background layers are made transparent where they overlap. Both layers are drawn normal everywhere else.

Invert blend modes:

The following blend modes either invert or cancel out colors depending on colors of the background layer. These blend modes look for variations between top and background layers. For example, you can use difference or exclusion blend modes on two imagery layers of forest covers to visualize how forest covers changed from one year to another.

The invert blend mode can be used to turn any light basemap into a dark basemap to accommodate those who work in low-light conditions. The following screenshots show how setting the invert blend mode set on a feature layer with a simple renderer turns the world terrain basemap into a dark themed basemap in no time.

Blend mode	Description
difference	Subtracts the darker of the overlapping colors from the lighter color. When two pixels with the same value are subtracted, the result is black. Blending with black produces no change. Blending with white inverts the colors. This blending mode is useful for aligning layers with similar content.
exclusion	Similar to the `difference` blend mode, except that the resulting image is lighter overall. Overlapping areas with lighter color values are lightened, while darker overlapping color values become transparent.
minus	Subtracts colors of the top layer from colors of the background layer making the blend result darker. In the case of negative values, black is displayed.
invert	Inverts the background colors wherever the top and background layers overlap. The invert blend mode inverts the layer similar to a photographic negative.
reflect	This blend mode creates effects as if you added shiny objects or areas of light in the layer. Black pixels in the background layer are ignored as if they were transparent.

Default Value:"normal"

See also

Layer blending samples

declaredClass Inherited Property declaredClass Stringreadonly Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.7 Accessor since 4.0, declaredClass added at 4.7.

The name of the class. The declared class name is formatted as esri.folder.className.

effect Property effect Effect |null |undefinedautocast Since: ArcGIS Maps SDK for JavaScript 4.18 GeoRSSLayer since 4.3, effect added at 4.18.

Effect provides various filter functions that can be performed on the layer to achieve different visual effects similar to how image filters work. This powerful capability allows you to apply css filter-like functions to layers to create custom visual effects to enhance the cartographic quality of your maps. This is done by applying the desired effect to the layer's effect property as a string or an array of objects to set scale dependent effects.

Notes

Set featureEffect property if different effects need to be applied features that meet or fail a specified filter.
If all of the following four properties are applied, then they will be applied in this order: featureEffect, effect, opacity and blendMode.

Known Limitations

The effect is not supported in 3D SceneViews.
The effect cannot be applied to a layer with a heatmap renderer.
The effect is not supported in layers with featureReduction of type cluster enabled.
See print for known printing limitations.

Default Value:null

See also

Examples

// the following effect will be applied to the layer at all scales
// brightness will be applied first, then hue-rotate followed by contrast
// changing order of the effects will change the final result
layer.effect = "brightness(5) hue-rotate(270deg) contrast(200%)";

// set a scale dependent bloom effect on the layer
layer.effect = [
  {
    scale: 36978595,
    value: "drop-shadow(3px, 3px, 4px)"
  },
  {
    scale: 18489297,
    value: "drop-shadow(2px, 2px, 3px)"
  },
  {
    scale: 4622324,
    value: "drop-shadow(1px, 1px, 2px)"
  }
];

id Inherited Property id String Inherited from Layer

The unique ID assigned to the layer. If not set by the developer, it is automatically generated when the layer is loaded.

legendEnabled Property legendEnabled Boolean

Indicates whether the layer will be included in the legend.

Default Value:true

lineSymbol Property lineSymbol SimpleLineSymbol

Symbol used to represent line features from the GeoRSS feed.

listMode Inherited Property listMode String Inherited from Layer

Indicates how the layer should display in the LayerList widget. The possible values are listed below.

Value	Description
show	The layer is visible in the table of contents.
hide	The layer is hidden in the table of contents.
hide-children	If the layer is a GroupLayer, BuildingSceneLayer, KMLLayer, MapImageLayer, TileLayer or WMSLayer, hide the children layers from the table of contents.

Possible Values:"show" |"hide" |"hide-children"

Default Value:"show"

loadError Inherited Property loadError Errorreadonly Inherited from Layer

The Error object returned if an error occurred while loading.

Default Value:null

loadStatus Inherited Property loadStatus Stringreadonly Inherited from Layer

Represents the status of a load operation.

Value	Description
not-loaded	The object's resources have not loaded.
loading	The object's resources are currently loading.
loaded	The object's resources have loaded without errors.
failed	The object's resources failed to load. See loadError for more details.

Possible Values:"not-loaded" |"loading" |"failed" |"loaded"

Default Value:"not-loaded"

loadWarnings Inherited Property loadWarnings Object[]readonly Inherited from Layer

A list of warnings which occurred while loading.

loaded Inherited Property loaded Booleanreadonly Inherited from Layer

Indicates whether the layer's resources have loaded. When true, all the properties of the object can be accessed.

Default Value:false

maxScale Property maxScale Number

The maximum scale (most zoomed in) at which the layer is visible in the view. If the map is zoomed in beyond this scale, the layer will not be visible. A value of 0 means the layer does not have a maximum scale. The maxScale value should always be smaller than the minScale value, and greater than or equal to the service specification.

Default Value:0

Examples

// The layer will not be visible when the view is zoomed in beyond a scale of 1:1,000
layer.maxScale = 1000;

// The layer's visibility is not restricted to a maximum scale.
layer.maxScale = 0;

minScale Property minScale Number

The minimum scale (most zoomed out) at which the layer is visible in the view. If the map is zoomed out beyond this scale, the layer will not be visible. A value of 0 means the layer does not have a minimum scale. The minScale value should always be larger than the maxScale value, and lesser than or equal to the service specification.

Default Value:0

Examples

// The layer will not be visible when the view is zoomed out beyond a scale of 1:3,000,000
layer.minScale = 3000000;

// The layer's visibility is not restricted to a minimum scale.
layer.minScale = 0;

opacity Inherited Property opacity Number Inherited from Layer

The opacity of the layer. This value can range between 1 and 0, where 0 is 100 percent transparent and 1 is completely opaque.

Default Value:1

Example

// Makes the layer 50% transparent
layer.opacity = 0.5;

The parent to which the layer belongs.

persistenceEnabled Property persistenceEnabled Boolean Since: ArcGIS Maps SDK for JavaScript 4.28 GeoRSSLayer since 4.3, persistenceEnabled added at 4.28.

Enable persistence of the layer in a WebMap or WebScene.

Default Value:true

pointSymbol Property pointSymbol PictureMarkerSymbol |SimpleMarkerSymbol

Symbol used to represent point features from the GeoRSS feed.

polygonSymbol Property polygonSymbol SimpleFillSymbol

Symbol used to represent polygon features from the GeoRSS feed.

refreshInterval Property refreshInterval Number Since: ArcGIS Maps SDK for JavaScript 4.22 GeoRSSLayer since 4.3, refreshInterval added at 4.22.

Refresh interval of the layer in minutes. Value of 0 indicates no refresh.

Default Value:0

See also

refresh()
refresh event

Example

// the layer will be refreshed every 6 seconds.
layer.refreshInterval = 0.1;

title Property title String

The title of the layer used to identify it in places such as the Legend and LayerList widgets.

When the layer is loaded from a portal item, the title of the portal item will be used. If a layer is loaded as part of a webmap or a webscene, then the title of the layer as stored in the webmap/webscene will be used.

type Property type Stringreadonly

For GeoRSSLayer the type is always "geo-rss".

url Property url String

The URL pointing to a GeoRSS file. This must be publicly available.

visibilityTimeExtent Inherited Property visibilityTimeExtent TimeExtent |null |undefinedautocast Inherited from Layer Since: ArcGIS Maps SDK for JavaScript 4.30 Layer since 4.0, visibilityTimeExtent added at 4.30.

Specifies a fixed time extent during which a layer should be visible. This property can be used to configure a layer that does not have time values stored in an attribute field to work with time. Once configured, the TimeSlider widget will display the layer within the set time extent. In the case that only one of the start or end date values are available, the layer remains visible indefinitely in the direction where there is no time value.

Aerial imagery can capture seasonal variations in vegetation, water bodies, and land use patterns. For example, in agricultural regions, aerial imageries taken during different growing seasons provide insights into crop health and productivity. Defining a fixed time extent on imageries from specific time periods provides temporal context and facilitates focused analysis based on specific time periods or events.

Default Value:null

See also

Sample - GraphicsLayer with visibilityTimeExtent

visible Inherited Property visible Boolean Inherited from Layer

Indicates if the layer is visible in the View. When false, the layer may still be added to a Map instance that is referenced in a view, but its features will not be visible in the view.

Default Value:true

Example

// The layer is no longer visible in the view
layer.visible = false;

// Watch for changes in the layer's visibility
// and set the visibility of another layer when it changes
reactiveUtils.watch(
  () => layer.visible,
  (visible) => {
    if (visible) {
      anotherLayer.visible = true;
    } else {
      anotherLayer.visible = false;
    }
  }
);

Method Overview

Show inherited methods

Hide inherited methods

Return Type	Summary	Class
	Adds one or more handles which are to be tied to the lifecycle of the object.	Accessor
	Cancels a load() operation if it is already in progress.	Layer
Promise<LayerView>	Called by the views, such as MapView and SceneView, when the layer is added to the Map.layers collection and a layer view must be created for it.	Layer
	Destroys the layer and any associated resources (including its portalItem, if it is a property on the layer).	Layer
Boolean	Emits an event on the instance.	Layer
Boolean	Indicates whether there is an event listener on the instance that matches the provided event name.	Layer
Boolean	Returns true if a named group of handles exist.	Accessor
Boolean	`isFulfilled()` may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected).	Layer
Boolean	`isRejected()` may be used to verify if creating an instance of the class is rejected.	Layer
Boolean	`isResolved()` may be used to verify if creating an instance of the class is resolved.	Layer
Promise	Loads the resources referenced by this class.	Layer
Object	Registers an event handler on the instance.	Layer
	Fetches all the data for the layer.	GeoRSSLayer
	Removes a group of handles owned by the object.	Accessor
Promise	`when()` may be leveraged once an instance of the class is created.	Layer

Method Details

addHandles Inherited Method addHandles(handleOrHandles, groupKey) Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, addHandles added at 4.25.

Adds one or more handles which are to be tied to the lifecycle of the object. The handles will be removed when the object is destroyed.

// Manually manage handles
const handle = reactiveUtils.when(
  () => !view.updating,
  () => {
    wkidSelect.disabled = false;
  },
  { once: true }
);

this.addHandles(handle);

// Destroy the object
this.destroy();

Parameters

handleOrHandles WatchHandle|WatchHandle []

Handles marked for removal once the object is destroyed.

groupKey *

optional

Key identifying the group to which the handles should be added. All the handles in the group can later be removed with Accessor.removeHandles(). If no key is provided the handles are added to a default group.

cancelLoad Inherited Method cancelLoad() Inherited from Layer

Cancels a load() operation if it is already in progress.

createLayerView Inherited Method createLayerView(view, options){Promise<LayerView>} Inherited from Layer

Called by the views, such as MapView and SceneView, when the layer is added to the Map.layers collection and a layer view must be created for it. This method is used internally and there is no use case for invoking it directly.

Parameters

view *

The parent view.

options Object

optional

An object specifying additional options. See the object specification table below for the required properties of this object.

Specification

signal AbortSignal

optional

A signal to abort the creation of the layerview.

Returns

Type	Description
Promise<LayerView>	Resolves with a LayerView instance.

See also

Sample - Custom WebGL layer view

destroy Inherited Method destroy() Inherited from Layer Since: ArcGIS Maps SDK for JavaScript 4.17 Layer since 4.0, destroy added at 4.17.

Destroys the layer and any associated resources (including its portalItem, if it is a property on the layer). The layer can no longer be used once it has been destroyed.

The destroyed layer will be removed from its parent object like Map, WebMap, WebScene, Basemap, Ground, or GroupLayer.

See also

emit Inherited Method emit(type, event){Boolean} Inherited from Layer Since: ArcGIS Maps SDK for JavaScript 4.5 Layer since 4.0, emit added at 4.5.

Emits an event on the instance. This method should only be used when creating subclasses of this class.

Parameters

type String

The name of the event.

event Object

optional

The event payload.

Returns

Type	Description
Boolean	`true` if a listener was notified

hasEventListener Inherited Method hasEventListener(type){Boolean} Inherited from Layer

Indicates whether there is an event listener on the instance that matches the provided event name.

Parameter

type String

The name of the event.

Returns

Type	Description
Boolean	Returns true if the class supports the input event.

hasHandles Inherited Method hasHandles(groupKey){Boolean} Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, hasHandles added at 4.25.

Returns true if a named group of handles exist.

Parameter

groupKey *

optional

A group key.

Returns

Type	Description
Boolean	Returns `true` if a named group of handles exist.

Example

// Remove a named group of handles if they exist.
if (obj.hasHandles("watch-view-updates")) {
  obj.removeHandles("watch-view-updates");
}

isFulfilled Inherited Method isFulfilled(){Boolean} Inherited from Layer

isFulfilled() may be used to verify if creating an instance of the class is fulfilled (either resolved or rejected). If it is fulfilled, true will be returned.

Returns

Type	Description
Boolean	Indicates whether creating an instance of the class has been fulfilled (either resolved or rejected).

isRejected Inherited Method isRejected(){Boolean} Inherited from Layer

isRejected() may be used to verify if creating an instance of the class is rejected. If it is rejected, true will be returned.

Returns

Type	Description
Boolean	Indicates whether creating an instance of the class has been rejected.

isResolved Inherited Method isResolved(){Boolean} Inherited from Layer

isResolved() may be used to verify if creating an instance of the class is resolved. If it is resolved, true will be returned.

Returns

Type	Description
Boolean	Indicates whether creating an instance of the class has been resolved.

load Inherited Method load(signal){Promise} Inherited from Layer

Loads the resources referenced by this class. This method automatically executes for a View and all of the resources it references in Map if the view is constructed with a map instance.

This method must be called by the developer when accessing a resource that will not be loaded in a View.

The load() method only triggers the loading of the resource the first time it is called. The subsequent calls return the same promise.

It's possible to provide a signal to stop being interested into a Loadable instance load status. When the signal is aborted, the instance does not stop its loading process, only cancelLoad can abort it.

Parameter

signal AbortSignal

optional

Signal object that can be used to abort the asynchronous task. The returned promise will be rejected with an Error named AbortError when an abort is signaled. See also AbortController for more information on how to construct a controller that can be used to deliver abort signals.

Returns

Type	Description
Promise	Resolves when the resources have loaded.

on Inherited Method on(type, listener){Object} Inherited from Layer

Registers an event handler on the instance. Call this method to hook an event with a listener.

Parameters

type String|String []

An event or an array of events to listen for.

listener Function

The function to call when the event fires.

Returns

Type Description

Object

Returns an event handler with a remove() method that should be called to stop listening for the event(s).

Property	Type	Description
remove	Function	When called, removes the listener from the event.

Example

view.on("click", function(event){
  // event is the event handle returned after the event fires.
  console.log(event.mapPoint);
});

refresh Method refresh() Since: ArcGIS Maps SDK for JavaScript 4.22 GeoRSSLayer since 4.3, refresh added at 4.22.

Fetches all the data for the layer.

See also

refreshInterval
refresh event

removeHandles Inherited Method removeHandles(groupKey) Inherited from Accessor Since: ArcGIS Maps SDK for JavaScript 4.25 Accessor since 4.0, removeHandles added at 4.25.

Removes a group of handles owned by the object.

Parameter

groupKey *

optional

A group key or an array or collection of group keys to remove.

Example

obj.removeHandles(); // removes handles from default group

obj.removeHandles("handle-group");
obj.removeHandles("other-handle-group");

when Inherited Method when(callback, errback){Promise} Inherited from Layer Since: ArcGIS Maps SDK for JavaScript 4.6 Layer since 4.0, when added at 4.6.

when() may be leveraged once an instance of the class is created. This method takes two input parameters: a callback function and an errback function. The callback executes when the instance of the class loads. The errback executes if the instance of the class fails to load.

Parameters

callback Function

optional

The function to call when the promise resolves.

errback Function

optional

The function to execute when the promise fails.

Returns

Type	Description
Promise	Returns a new promise for the result of `callback` that may be used to chain additional functions.

Example

// Although this example uses MapView, any class instance that is a promise may use when() in the same way
let view = new MapView();
view.when(function(){
  // This function will execute once the promise is resolved
}, function(error){
  // This function will execute if the promise is rejected due to an error
});

Event Overview

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Type	Summary	Class
{view: View,layerView: LayerView}	Fires after the layer's LayerView is created and rendered in a view.	Layer
{view: View,error: Error}	Fires when an error emits during the creation of a LayerView after a layer has been added to the map.	Layer
{view: View,layerView: LayerView}	Fires after the layer's LayerView is destroyed and no longer renders in a view.	Layer
{dataChanged: Boolean}	Fires if the layer has the refreshInterval set or when refresh() method is called.	GeoRSSLayer

Event Details

layerview-create Inherited Event layerview-create Inherited from Layer

Fires after the layer's LayerView is created and rendered in a view.

Properties

view View

The view in which the layerView was created.

layerView LayerView

The LayerView rendered in the view representing the layer in layer.

See also

View.whenLayerView()

Example

// This function will fire each time a layer view is created for this
// particular view.
layer.on("layerview-create", function(event){
  // The LayerView for the layer that emitted this event
  event.layerView;
});

layerview-create-error Inherited Event layerview-create-error Inherited from Layer

Fires when an error emits during the creation of a LayerView after a layer has been added to the map.

Properties

view View

The view that failed to create a layerview for the layer emitting this event.

error Error

An error object describing why the layer view failed to create.

See also

View.whenLayerView()

Example

// This function fires when an error occurs during the creation of the layer's layerview
layer.on("layerview-create-error", function(event) {
  console.error("LayerView failed to create for layer with the id: ", layer.id, " in this view: ", event.view);
});

layerview-destroy Inherited Event layerview-destroy Inherited from Layer

Fires after the layer's LayerView is destroyed and no longer renders in a view.

Properties: view View

The view in which the layerView was destroyed.

layerView LayerView

The destroyed LayerView representing the layer.

refresh Event refresh Since: ArcGIS Maps SDK for JavaScript 4.22 GeoRSSLayer since 4.3, refresh added at 4.22.

Fires if the layer has the refreshInterval set or when refresh() method is called. The event payload indicates if the layer's data has changed.

Property

dataChanged Boolean

Indicates if the layer's data has changed.

See also

refreshInterval
refresh()

Example

// listen to layer's refresh event to fetch the attachments
// for the updated features.
layer.on("refresh", function(event){
  if (event.dataChanged){
    const query = layer.createQuery();
    layer.queryObjectIds(query).then(function (objectIds) {
      let attachmentQuery = {
        objectIds: objectIds,
        definitionExpression: layer.definitionExpression,
        attachmentTypes: ["image/jpeg"]
      };
      layer.queryAttachments(attachmentQuery).then(function (attachments) {
        attachmentQuery.objectIds.forEach(function (objectId) {
          if (attachments[objectId]) {
            // process the updated attachments
            let attachment = attachments[objectId];
          }
        });
      })
      .catch(function (error) {
        console.log("attachment query error", error);
      });
    });
  }
});