ESRI javascript featureLayer.graphics - arcgis

Question

I'm working on a map that uses FeatureLayer.Mode_ONDEMAND. To see certain layer, I pass in a project ID using featureLayer.setDefinitionExpression. Where such layer exists, I see it. What I want to know is how to detect when no layer exists. I want to print an alert to the viewer instead of showing just a blank map. Here's my code:
function init() {
map = new esri.Map("mapDiv", {
basemap: "topo",
zoom: 9
});
var featureLayer = new esri.layers.FeatureLayer("http://services.arcgis.com/v01g34asdwfAi/arcgis/rest/services/Projects/FeatureServer/0",{
mode: esri.layers.FeatureLayer.MODE_ONDEMAND,
outFields: ["*"],
opacity: 1
});
featureLayer.setDefinitionExpression("SrvyDescID=\'' . htmlspecialchars($ProjectID) . '\'");
console.log(featureLayer.graphics);
console.log(featureLayer.graphics[0]);
map.addLayer(featureLayer);
}
What I learned is when the project is valid, feature.graphics will return an array. But I'm unable to treat it like an array. For example:
console.log(featureLayer.graphics) returns an array object
but
console.log(featureLayer.graphics[0]) returns "undefined".
featureLayer.graphic.length also doesn't work. How do I use this array object to let me know that a layer is displayed on the map?
Attached is a screenshot of the console log. Thanks for your help.

Answer 1

I needed to catch "update-end" event. Final code:
map = new esri.Map("mapDiv", {
center: [-118.30, 34.3],
zoom: 8,
basemap: "topo"
});
on(map, "update-end", function(){ // update-end event will execute after the layer has been added to the map
if(featureLayer.graphics.length >= 1)
{
// do your thing
}
})
var featureLayer = new
esri.layers.FeatureLayer("http://services.arcgis.com/v01gqwMseaqNAi/arcgis/rest/services/Project_boundaries_021616/FeatureServer/0",{
mode: esri.layers.FeatureLayer.MODE_ONDEMAND,
outFields: ["*"],
opacity: 1
});
featureLayer.setDefinitionExpression("SrvyDescID=\'' . htmlspecialchars($SDID) . '\'");
map.addLayer(featureLayer);