fix: jsonValue() type is generic (#6865)

During the migration to TS we changed `jsonValue` so it returned `<Record<string, unknown>>`. This is only true if all the JSON values it returns are objects; but it could return an array, a string, a number, etc. Therefore we make the type generic, setting the default to `unknown`, so the user has control over the type.
puppeteer · Feb 11, 2021 · bdaba78 · bdaba78
1 parent 63d48b2
commit bdaba78
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diff --git a/src/common/JSHandle.ts b/src/common/JSHandle.ts
@@ -243,17 +243,17 @@ export class JSHandle {
    * on the object in page and consequent {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse | JSON.parse} in puppeteer.
    * **NOTE** The method throws if the referenced object is not stringifiable.
    */
-  async jsonValue(): Promise<Record<string, unknown>> {
+  async jsonValue<T = unknown>(): Promise<T> {
     if (this._remoteObject.objectId) {
       const response = await this._client.send('Runtime.callFunctionOn', {
         functionDeclaration: 'function() { return this; }',
         objectId: this._remoteObject.objectId,
         returnByValue: true,
         awaitPromise: true,
       });
-      return helper.valueFromRemoteObject(response.result);
+      return helper.valueFromRemoteObject(response.result) as T;
     }
-    return helper.valueFromRemoteObject(this._remoteObject);
+    return helper.valueFromRemoteObject(this._remoteObject) as T;
   }
 
   /**

diff --git a/test/evaluation.spec.ts b/test/evaluation.spec.ts
@@ -278,7 +278,7 @@ describe('Evaluation specs', function () {
 
       const windowHandle = await page.evaluateHandle(() => window);
       const errorText = await windowHandle
-        .jsonValue()
+        .jsonValue<string>()
         .catch((error_) => error_.message);
       const error = await page
         .evaluate<(errorText: string) => Error>((errorText) => {

diff --git a/test/jshandle.spec.ts b/test/jshandle.spec.ts
@@ -114,9 +114,26 @@ describe('JSHandle', function () {
       const { page } = getTestState();
 
       const aHandle = await page.evaluateHandle(() => ({ foo: 'bar' }));
-      const json = await aHandle.jsonValue();
+      const json = await aHandle.jsonValue<Record<string, string>>();
       expect(json).toEqual({ foo: 'bar' });
     });
+
+    it('works with jsonValues that are not objects', async () => {
+      const { page } = getTestState();
+
+      const aHandle = await page.evaluateHandle(() => ['a', 'b']);
+      const json = await aHandle.jsonValue<string[]>();
+      expect(json).toEqual(['a', 'b']);
+    });
+
+    it('works with jsonValues that are primitives', async () => {
+      const { page } = getTestState();
+
+      const aHandle = await page.evaluateHandle(() => 'foo');
+      const json = await aHandle.jsonValue<string>();
+      expect(json).toEqual('foo');
+    });
+
     itFailsFirefox('should not work with dates', async () => {
       const { page } = getTestState();