fix(reactive): avoid unneccessary reaction

packages/reactive/src/__tests__/autorun.spec.ts

@@ -741,3 +741,19 @@ test('reaction recollect dependencies', () => {
   expect(fn2).toBeCalledTimes(2)
   expect(trigger2).toBeCalledTimes(2)
 })
+
+test('avoid unnecessary reaction', () => {
+  const obs = observable<any>({
+    aa: { v: 1 },
+  })
+  const fn1 = jest.fn()
+
+  reaction(() => {
+    fn1()
+    return obs.aa.v
+  })
+
+  obs.aa = obs.aa
+
+  expect(fn1).toBeCalledTimes(1)
+})

packages/reactive/src/handlers.ts

@@ -207,7 +207,12 @@ export const baseHandlers: ProxyHandler<any> = {
     }
     const hadKey = hasOwnProperty.call(target, key)
     const newValue = createObservable(target, key, value)
-    const oldValue = target[key]
+
+    // If the old value has already generated an observable result,
+    // directly use observableResult compapre to value to avoid unnecessary reactions
+    const observableResult = RawProxy.get(target[key])
+    const oldValue = observableResult ? observableResult : target[key]
+
     target[key] = newValue // use Reflect.set is too slow
     if (!hadKey) {
       runReactionsFromTargetKey({