feat: setProperty on Observable (#8521)

* feat: setProperty on Observable

* refactor: add missing whitespace

Co-Authored-By: Vasil Trifonov <v.trifonov@gmail.com>

Co-authored-by: Vasil Trifonov <v.trifonov@gmail.com>

api-reports/NativeScript.api.md

@@ -1503,6 +1503,8 @@ export class Observable {
     removeEventListener(eventNames: string, callback?: any, thisArg?: any);
 
     set(name: string, value: any): void;
+
+    setProperty(name: string, value: any): void;
     //@endprivate
 }
 
@@ -2425,10 +2427,11 @@ export class TabViewItem extends ViewBase {
 
 // @public
 export interface TapGestureEventData extends GestureEventData {
-    getPointerCount(): number;
+   getPointerCount(): number;
     getX(): number;
     getY(): number;
-}
+
+ }
 
 // @public
 export interface Template {

nativescript-core/data/observable/observable.d.ts

@@ -129,6 +129,11 @@ export class Observable {
      */
     set(name: string, value: any): void;
 
+    /**
+     * Updates the specified property with the provided value and raises a property change event and a specific change event based on the property name.
+     */
+    setProperty(name: string, value: any): void;
+
     /**
      * Gets the value of the specified property.
      */

nativescript-core/data/observable/observable.ts

@@ -57,6 +57,22 @@ export class Observable implements ObservableDefinition {
         this.notifyPropertyChange(name, newValue, oldValue);
     }
 
+    public setProperty(name: string, value: any) {
+        const oldValue = this[name];
+        if (this[name] === value) {
+            return;
+        }
+        this[name] = value;
+        this.notifyPropertyChange(name, value, oldValue);
+
+        const specificPropertyChangeEventName = name + "Change";
+        if (this.hasListeners(specificPropertyChangeEventName)) {
+            const eventData = this._createPropertyChangeData(name, value, oldValue);
+            eventData.eventName = specificPropertyChangeEventName;
+            this.notify(eventData);
+        }
+    }
+
     public on(eventNames: string, callback: (data: EventData) => void, thisArg?: any) {
         this.addEventListener(eventNames, callback, thisArg);
     }