arcgis js中map,layer,graphics

1. Map: The Map class is the central component of the ArcGIS API for JavaScript. It provides the interface for creating and managing a map and its layers. The Map class is responsible for managing the map extent, spatial reference, and other properties such as the map's zoom level.

2. Layer: The Layer class represents a single layer in a map. It can be a feature layer, tile layer, image layer, or any other type of layer supported by the ArcGIS API for JavaScript. Layers are added to the map using the Map.addLayer() method. The Layer class provides methods for querying and manipulating the layer's data.

3. Graphics: The Graphics class is used to display graphics on a map. Graphics are typically used to display temporary data such as user-generated features or analysis results. A graphic can represent a point, line, polygon, or other type of geometry. The Graphics class provides methods for adding, updating, and removing graphics from the map.