fix(platform-browser): support 0/false/null values in transfer_state (#22179)

Issue #22178

PR Close #22179

packages/platform-browser/src/browser/transfer_state.ts

@@ -93,7 +93,9 @@ export class TransferState {
   /**
    * Get the value corresponding to a key. Return `defaultValue` if key is not found.
    */
-  get<T>(key: StateKey<T>, defaultValue: T): T { return this.store[key] as T || defaultValue; }
+  get<T>(key: StateKey<T>, defaultValue: T): T {
+    return this.store[key] !== undefined ? this.store[key] as T : defaultValue;
+  }
 
   /**
    * Set the value corresponding to a key.

packages/platform-browser/test/browser/transfer_state_spec.ts

@@ -70,6 +70,27 @@ import {DOCUMENT} from '@angular/platform-browser/src/dom/dom_tokens';
       expect(transferState.hasKey(TEST_KEY)).toBe(true);
     });
 
+    it('supports setting and accessing value \'0\' via get', () => {
+      const transferState: TransferState = TestBed.get(TransferState);
+      transferState.set(TEST_KEY, 0);
+      expect(transferState.get(TEST_KEY, 20)).toBe(0);
+      expect(transferState.hasKey(TEST_KEY)).toBe(true);
+    });
+
+    it('supports setting and accessing value \'false\' via get', () => {
+      const transferState: TransferState = TestBed.get(TransferState);
+      transferState.set(TEST_KEY, false);
+      expect(transferState.get(TEST_KEY, 20)).toBe(false);
+      expect(transferState.hasKey(TEST_KEY)).toBe(true);
+    });
+
+    it('supports setting and accessing value \'null\' via get', () => {
+      const transferState: TransferState = TestBed.get(TransferState);
+      transferState.set(TEST_KEY, null);
+      expect(transferState.get(TEST_KEY, 20)).toBe(null);
+      expect(transferState.hasKey(TEST_KEY)).toBe(true);
+    });
+
     it('supports removing keys', () => {
       const transferState: TransferState = TestBed.get(TransferState);
       transferState.set(TEST_KEY, 20);