topic How do I add multiple layers to the LayerList? in ArcGIS JavaScript Maps SDK Questions

How do I add multiple layers to the LayerList?

GregSalvador — Thu, 24 Aug 2017 14:26:26 GMT

Hi all,

I would like to add multiple layers to the LayerList dijit (using 3.21). I tried to add each layer to an array as it was added to the map and then reference the array when making the LayerList, but this left out all of the sublayers. here is my code:

var layerArray = new Array();
var tempLayer = new ArcGISDynamicMapServiceLayer(
"https://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Population_World/MapServer");
layerArray.push(map.addLayer(tempLayer));

.....repeated with different layers.......

//layerlist widget initialization
var layerListWidget = new LayerList({
map: map,
layers: layerArray
}, "layerList");
layerListWidget.startup();

Is there a way to add all of the layers (and sublayers) to the layerList Dijit programmatically?

Re: How do I add multiple layers to the LayerList?

RobertScheitlin__GISP — Thu, 24 Aug 2017 15:37:19 GMT

Greg,

You will see in the widget documentation that if you do not add a layers property in the LayerList widget constructor then it will display all layers that are in the map. You do need to wait for the layers to be added to the map before creating the LayerList widget though.

Re: How do I add multiple layers to the LayerList?

GregSalvador — Thu, 24 Aug 2017 16:07:28 GMT

Thank you Robert. I don't know how I missed this tidbit, but thanks

Re: How do I add multiple layers to the LayerList?

GregSalvador — Thu, 24 Aug 2017 17:04:28 GMT

So I have another question: how do i remove a layer from the layerList? I noticed that one of the layers added is the basemap, and I don't want users to be able to toggle it on and off. I didnt see a remove function, so do I have to instead define all of the layers that I want in the list and omit the basemap Layer?

Re: How do I add multiple layers to the LayerList?

RobertScheitlin__GISP — Thu, 24 Aug 2017 17:17:47 GMT

Do I have to instead define all of the layers that I want in the list and omit the basemap Layer?

Correct

Our you could wait for the load event on the widget and manipulate the layers array.

Re: How do I add multiple layers to the LayerList?

GregSalvador — Fri, 25 Aug 2017 13:58:52 GMT

Hi again.
I am trying to wait for the load event on the widget and the manipulate the layers array. I seem to be doing something wrong, as i get a browser error saying "TypeError: c is null". The problem seems to be with my on("load") statement, but all of the examples I have seen seem to do it similarly. I checked, and my require "dojo/on" and the function order is the same, and I've called the on("load") function after I have declared the LayerList. Is there a step i am missing somewhere? Here is my code:
require([
"esri/map",
"esri/arcgis/utils",
"esri/layers/ArcGISDynamicMapServiceLayer",
"esri/dijit/LayerList",
"esri/dijit/BasemapGallery",
"dijit/layout/BorderContainer",
"dijit/layout/ContentPane",
"dojo/parser",
"dojo/on",
"dojo/domReady!"
], function (Map, arcgisUtils, ArcGISDynamicMapServiceLayer, LayerList, BasemapGallery, parser, on) {
...declaring layers and map object.....

//layerlist widget initialization
var layerListWidget = new LayerList({
map: map,
}, "layerList");
layerListWidget.startup();
on(layerListWidget, "load", function (item) {
item.layers.reverse();
item.layers.pop();
item.layers.reverse();
});

Re: How do I add multiple layers to the LayerList?

RobertScheitlin__GISP — Sat, 11 Dec 2021 16:30:04 GMT

Greg,

Your requires and corresponding vars are out of order.

You have:

require([
"esri/map",
"esri/arcgis/utils",
"esri/layers/ArcGISDynamicMapServiceLayer",
"esri/dijit/LayerList",
"esri/dijit/BasemapGallery",
"dijit/layout/BorderContainer",
"dijit/layout/ContentPane",
"dojo/parser",
"dojo/on",
"dojo/domReady!"
], function (Map, arcgisUtils, ArcGISDynamicMapServiceLayer, LayerList, BasemapGallery, parser, on) {‍‍‍‍‍‍‍‍‍‍‍‍

Should be:

require([
"esri/map",
"esri/arcgis/utils",
"esri/layers/ArcGISDynamicMapServiceLayer",
"esri/dijit/LayerList",
"esri/dijit/BasemapGallery",
"dojo/parser",
"dojo/on",
"dijit/layout/BorderContainer",
"dijit/layout/ContentPane",
"dojo/domReady!"
], function (Map, arcgisUtils, ArcGISDynamicMapServiceLayer, LayerList, BasemapGallery, parser, on) {‍‍‍‍‍‍‍‍‍‍‍‍

Re: How do I add multiple layers to the LayerList?

GregSalvador — Fri, 25 Aug 2017 14:26:45 GMT

ok, I get it, i think. All of the requires with a corresponding variable have to be first, followed the the requires that don't have a variable? do the requires with a variable need to be in any specific order(as long as they stay synced up)?

Re: How do I add multiple layers to the LayerList?

RobertScheitlin__GISP — Fri, 25 Aug 2017 14:29:40 GMT

As long as they stay synced up (listed in the same order) then you are fine.