What you'll want to do is use the dojo/promise/all. This executes multiple tasks and, when they are all complete, returns an object with the results of the tasks in the same order as the tasks were originally supplied. The code below shows an example using IdentifyTask on multiple services.
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<!--The viewport meta tag is used to improve the presentation and behavior of the samples
on iOS devices-->
<meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
<title>Identify with Popup</title>
<link rel="stylesheet" href="http://js.arcgis.com/3.8/js/esri/css/esri.css">
<style>
html, body, #map {
height: 100%;
width: 100%;
margin: 0;
padding: 0;
}
</style>
<script>var dojoConfig = { parseOnLoad: true };</script>
<script src="http://js.arcgis.com/3.8/"></script>
<script>
var map;
var identifyTask, identifyParams, idPoint;
var identifyResults;
require([
"esri/map", "esri/dijit/Popup", "dojo/promise/all", "dojo/domReady!"
], function (
Map, Popup, All
) {
var popup = new Popup({
fillSymbol: new esri.symbol.SimpleFillSymbol(esri.symbol.SimpleFillSymbol.STYLE_SOLID, new esri.symbol.SimpleLineSymbol(esri.symbol.SimpleLineSymbol.STYLE_SOLID, new dojo.Color([255, 0, 0]), 2), new dojo.Color([255, 255, 0, 0.25]))
}, dojo.create("div"));
map = new Map("map", {
basemap: "satellite",
center: [-83.275, 42.573],
zoom: 18,
infoWindow: popup
});
dojo.connect(map, "onLoad", mapReady);
var landBaseLayer = new esri.layers.ArcGISDynamicMapServiceLayer("http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/BloomfieldHillsMichigan/Parcels/MapServer", { opacity: .55 });
map.addLayer(landBaseLayer);
var militaryLayer = new esri.layers.ArcGISDynamicMapServiceLayer("http://sampleserver6.arcgisonline.com/arcgis/rest/services/Military/MapServer", { opacity: .55 });
map.addLayer(militaryLayer);
console.log(militaryLayer.declaredClass);
function mapReady(map) {
dojo.connect(map, "onClick", runIdentifies);
}
function runIdentifies(evt) {
identifyResults = [];
idPoint = evt.mapPoint;
var layers = dojo.map(map.layerIds, function (layerId) {
return map.getLayer(layerId);
});
layers = dojo.filter(layers, function (layer) {
if (layer.visibleLayers[0] !== -1) {
return layer.getImageUrl && layer.visible
}
}); //Only dynamic layers have the getImageUrl function. Filter so you only query visible dynamic layers
var tasks = dojo.map(layers, function (layer) {
return new esri.tasks.IdentifyTask(layer.url);
}); //map each visible dynamic layer to a new identify task, using the layer url
var defTasks = dojo.map(tasks, function (task) {
return new dojo.Deferred();
}); //map each identify task to a new dojo.Deferred
var params = createIdentifyParams(layers, evt);
var promises = [];
for (i = 0; i < tasks.length; i++) {
promises.push(tasks.execute(params)); //Execute each task
}
var allPromises = new All(promises);
allPromises.then(function (r) { showIdentifyResults(r, tasks); });
}
function showIdentifyResults(r, tasks) {
var results = [];
var taskUrls = [];
r = dojo.filter(r, function (result) {
return r[0];
});
for (i = 0; i < r.length; i++) {
results = results.concat(r);
for (j = 0; j < r.length; j++) {
taskUrls = taskUrls.concat(tasks.url);
}
}
results = dojo.map(results, function (result, index) {
var feature = result.feature;
var layerName = result.layerName;
var serviceUrl = taskUrls[index];
feature.attributes.layerName = result.layerName;
var template = new esri.InfoTemplate("", "Service Url: " + serviceUrl + "<br/><br/>Layer name: " + result.layerName + "<br/><br/> Object Id: ${OBJECTID}");
feature.setInfoTemplate(template);
var resultGeometry = feature.geometry;
var resultType = resultGeometry.type;
return feature;
});
if (results.length === 0) {
map.infoWindow.clearFeatures();
} else {
map.infoWindow.setFeatures(results);
}
map.infoWindow.show(idPoint);
return results;
}
function createIdentifyParams(layers, evt) {
var identifyParamsList = [];
identifyParamsList.length = 0;
dojo.forEach(layers, function (layer) {
var idParams = new esri.tasks.IdentifyParameters();
idParams.width = map.width;
idParams.height = map.height;
idParams.geometry = evt.mapPoint;
idParams.mapExtent = map.extent;
idParams.layerOption = esri.tasks.IdentifyParameters.LAYER_OPTION_VISIBLE;
var visLayers = layer.visibleLayers;
if (visLayers !== -1) {
var subLayers = [];
for (var i = 0; i < layer.layerInfos.length; i++) {
if (layer.layerInfos.subLayerIds == null)
subLayers.push(layer.layerInfos.id);
}
idParams.layerIds = subLayers;
} else {
idParams.layerIds = [];
}
idParams.tolerance = 3;
idParams.returnGeometry = true;
identifyParamsList.push(idParams);
});
return identifyParamsList;
}
});
</script>
</head>
<body>
<div id="map"></div>
</body>
</html>
