GraphicsLayerView

// Highlight features based on a query result

// Add a new set of highlight options to the view's highlights collection
view.highlights.push({
  name: "oaks",
  color: "forestgreen",
  haloOpacity: 0.8,
  fillOpacity: 0.3
});

// A handler can be used to remove any previous highlight when applying a new one
let highlight;

// Query for particualar features in a layer and then highlight them with the specified options
view.whenLayerView(treesLayer).then((layerView) => {
  let query = treesLayer.createQuery();
  query.where = "type = 'Quercus'";

  treesLayer.queryFeatures(query).then((result) => {
    // Remove any previous highlight, if it exists
    highlight?.remove();
    // Apply the "oaks" highlight options to the corresponding tree features
    highlight = layerView.highlight(result.features, {name: "oaks"});
  });
});

// Use the default highlights collection to apply a highlight to features when you hover over them

// A handler can be used to remove any previous highlight when applying a new one
let hoverHighlight;

view.on("pointer-move", (event) => {
  // Search for the first feature in the featureLayer at the hovered location
  view.hitTest(event, { include: layer }).then((response) => {
    if (response.results[0]) {
      const graphic = response.results[0].graphic;
      view.whenLayerView(graphic.layer).then((layerView) => {
        // Remove any previous highlight, if it exists
        hoverHighlight?.remove();
        // Highlight the hit features with the temporary highlight options, which are pre-configured for this use case
        hoverHighlight = layerView.highlight(graphic, { name: "temporary" });
      });
    }
  });
});

let layer = new GraphicsLayer();

// returns all the graphics from the layer view
const layerView = await view.whenLayerView(layer);
await reactiveUtils.whenOnce(() => !layerView.updating);
const results = await layerView.queryGraphics();
console.log(results);  // prints the array of client-side graphics to the console