Hi Puthran Joshua,
Please see the sample below.
I did take a basic tutorial from Esri - Add layers to a map | ArcGIS API for JavaScript 4.15 - and extend this with a LayerList widget and a GroupLayer, just to prove that it is possible to add FeatureLayers to a GroupLayer.
From here you could extend the application further, with your own data of course.
Hope this helps.
BR,
Egge-Jan
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="initial-scale=1, maximum-scale=1, user-scalable=no">
<title>ArcGIS JavaScript Tutorials: Add a GroupLayer to a LayerList widget</title>
<link rel="stylesheet" href="https://js.arcgis.com/4.15/esri/css/main.css">
<script src="https://js.arcgis.com/4.15/"></script>
<style>
html, body, #viewDiv {
padding: 0;
margin: 0;
height: 100%;
width: 100%;
}
</style>
<script>
require([
"esri/Map",
"esri/views/MapView",
"esri/layers/FeatureLayer",
"esri/layers/GroupLayer",
"esri/widgets/LayerList"
], function(Map, MapView, FeatureLayer, GroupLayer, LayerList) {
var map = new Map({
basemap: "topo-vector"
});
var view = new MapView({
container: "viewDiv",
map: map,
center: [-118.80543,34.02700],
zoom: 13
});
var trailheadsLayer = new FeatureLayer({
url: "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0"
});
var trailsLayer = new FeatureLayer({
url: "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trails/FeatureServer/0"
});
var parksLayer = new FeatureLayer({
url: "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Parks_and_Open_Space/FeatureServer/0"
});
var layerList = new LayerList({
view: view
});
view.ui.add(layerList, {
position: "top-left"
});
var myGroupLayer = new GroupLayer({
title: "My GroupLayer",
layers: [parksLayer, trailsLayer, trailheadsLayer]
});
map.add(myGroupLayer);
});
</script>
</head>
<body>
<div id="viewDiv"></div>
</body>
</html>