This sample demonstrates how you can change which features are display on the map. Use the buttons to apply or reset definition expression to display only the features for 'Tree Mainenance'.
How it works
You achieve this by setting the definitionExpression property on an AGSFeatureLayer. Set the expression to be an SQL where clause such as "req_Type = 'Tree Maintenance or Damage'". This will limit the features that are displayed on the map.