feat: implement immutable locator operations (#10638)

docs/api/puppeteer.locator.clone.md

@@ -0,0 +1,19 @@
+---
+sidebar_label: Locator.clone
+---
+
+# Locator.clone() method
+
+Clones the locator.
+
+#### Signature:
+
+```typescript
+class Locator {
+  clone(): Locator<T>;
+}
+```
+
+**Returns:**
+
+[Locator](./puppeteer.locator.md)&lt;T&gt;

docs/api/puppeteer.locator.md

@@ -16,15 +16,17 @@ export declare abstract class Locator<T> extends EventEmitter
 
 ## Properties
 
-| Property | Modifiers             | Type | Description                                                  |
+| Property | Modifiers             | Type   | Description                                                  |
-| -------- | --------------------- | ---- | ------------------------------------------------------------ |
+| -------- | --------------------- | ------ | ------------------------------------------------------------ |
-| \_       | <code>optional</code> | T    | Used for nominally typing [Locator](./puppeteer.locator.md). |
+| \_       | <code>optional</code> | T      | Used for nominally typing [Locator](./puppeteer.locator.md). |
+| timeout  | <code>readonly</code> | number |                                                              |
 
 ## Methods
 
 | Method                                                                                                 | Modifiers           | Description                                                                                                                                                                                                                              |
 | ------------------------------------------------------------------------------------------------------ | ------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | [click(this, options)](./puppeteer.locator.click.md)                                                   |                     |                                                                                                                                                                                                                                          |
+| [clone()](./puppeteer.locator.clone.md)                                                                |                     | Clones the locator.                                                                                                                                                                                                                      |
 | [fill(this, value, options)](./puppeteer.locator.fill.md)                                              |                     | Fills out the input identified by the locator using the provided value. The type of the input is determined at runtime and the appropriate fill-out method is chosen based on the type. contenteditable, selector, inputs are supported. |
 | [filter(predicate)](./puppeteer.locator.filter.md)                                                     |                     | <p>Creates an expectation that is evaluated against located values.</p><p>If the expectations do not match, then the locator will retry.</p>                                                                                             |
 | [hover(this, options)](./puppeteer.locator.hover.md)                                                   |                     |                                                                                                                                                                                                                                          |

docs/api/puppeteer.locator.settimeout.md

@@ -8,7 +8,7 @@ sidebar_label: Locator.setTimeout
 
 ```typescript
 class Locator {
-  setTimeout(timeout: number): this;
+  setTimeout(timeout: number): Locator<T>;
 }
 ```
 
@@ -20,4 +20,4 @@ class Locator {
 
 **Returns:**
 
-this
+[Locator](./puppeteer.locator.md)&lt;T&gt;

packages/puppeteer-core/src/api/locators/DelegatedLocator.ts

@@ -22,7 +22,7 @@ import {Locator, VisibilityOption} from './locators.js';
 /**
  * @internal
  */
-export class DelegatedLocator<T, U> extends Locator<U> {
+export abstract class DelegatedLocator<T, U> extends Locator<U> {
   #delegate: Locator<T>;
 
   constructor(delegate: Locator<T>) {
@@ -36,49 +36,62 @@ export class DelegatedLocator<T, U> extends Locator<U> {
     return this.#delegate;
   }
 
-  override setTimeout(timeout: number): this {
+  override setTimeout(timeout: number): DelegatedLocator<T, U> {
-    super.setTimeout(timeout);
+    const locator = super.setTimeout(timeout) as DelegatedLocator<T, U>;
-    this.#delegate.setTimeout(timeout);
+    locator.#delegate = this.#delegate.setTimeout(timeout);
-    return this;
+    return locator;
   }
 
-  override setVisibility<T extends Node, U extends T>(
+  override setVisibility<ValueType extends Node, NodeType extends Node>(
-    this: DelegatedLocator<T, U>,
+    this: DelegatedLocator<ValueType, NodeType>,
     visibility: VisibilityOption
-  ): Locator<U> {
+  ): DelegatedLocator<ValueType, NodeType> {
-    super.setVisibility(visibility);
+    const locator = super.setVisibility<NodeType>(
-    this.#delegate.setVisibility(visibility);
+      visibility
-    return this;
+    ) as DelegatedLocator<ValueType, NodeType>;
+    locator.#delegate = locator.#delegate.setVisibility<ValueType>(visibility);
+    return locator;
   }
 
-  override setWaitForEnabled<T extends Node, U extends T>(
+  override setWaitForEnabled<ValueType extends Node, NodeType extends Node>(
-    this: DelegatedLocator<T, U>,
+    this: DelegatedLocator<ValueType, NodeType>,
     value: boolean
-  ): Locator<U> {
+  ): DelegatedLocator<ValueType, NodeType> {
-    super.setWaitForEnabled(value);
+    const locator = super.setWaitForEnabled<NodeType>(
-    this.#delegate.setWaitForEnabled(value);
+      value
-    return this;
+    ) as DelegatedLocator<ValueType, NodeType>;
+    locator.#delegate = this.#delegate.setWaitForEnabled(value);
+    return locator;
   }
 
-  override setEnsureElementIsInTheViewport<T extends Element, U extends T>(
+  override setEnsureElementIsInTheViewport<
-    this: DelegatedLocator<T, U>,
+    ValueType extends Element,
+    ElementType extends Element,
+  >(
+    this: DelegatedLocator<ValueType, ElementType>,
     value: boolean
-  ): Locator<U> {
+  ): DelegatedLocator<ValueType, ElementType> {
-    super.setEnsureElementIsInTheViewport(value);
+    const locator = super.setEnsureElementIsInTheViewport<ElementType>(
-    this.#delegate.setEnsureElementIsInTheViewport(value);
+      value
-    return this;
+    ) as DelegatedLocator<ValueType, ElementType>;
+    locator.#delegate = this.#delegate.setEnsureElementIsInTheViewport(value);
+    return locator;
   }
 
-  override setWaitForStableBoundingBox<T extends Element, U extends T>(
+  override setWaitForStableBoundingBox<
-    this: DelegatedLocator<T, U>,
+    ValueType extends Element,
+    ElementType extends Element,
+  >(
+    this: DelegatedLocator<ValueType, ElementType>,
     value: boolean
-  ): Locator<U> {
+  ): DelegatedLocator<ValueType, ElementType> {
-    super.setWaitForStableBoundingBox(value);
+    const locator = super.setWaitForStableBoundingBox<ElementType>(
-    this.#delegate.setWaitForStableBoundingBox(value);
+      value
-    return this;
+    ) as DelegatedLocator<ValueType, ElementType>;
+    locator.#delegate = this.#delegate.setWaitForStableBoundingBox(value);
+    return locator;
   }
 
-  override _wait(): Observable<HandleFor<U>> {
+  abstract override _clone(): DelegatedLocator<T, U>;
-    throw new Error('Not implemented');
+  abstract override _wait(): Observable<HandleFor<U>>;
-  }
 }

packages/puppeteer-core/src/api/locators/FilteredLocator.ts

@@ -48,13 +48,20 @@ export class FilteredLocator<From, To extends From> extends DelegatedLocator<
     this.#predicate = predicate;
   }
 
+  override _clone(): FilteredLocator<From, To> {
+    return new FilteredLocator(
+      this.delegate.clone(),
+      this.#predicate
+    ).copyOptions(this);
+  }
+
   override _wait(options?: Readonly<ActionOptions>): Observable<HandleFor<To>> {
     return this.delegate._wait(options).pipe(
       mergeMap(handle => {
         return from(
           (handle as ElementHandle<Node>).frame.waitForFunction(
             this.#predicate,
-            {signal: options?.signal, timeout: this.timeout},
+            {signal: options?.signal, timeout: this._timeout},
             handle
           )
         ).pipe(

packages/puppeteer-core/src/api/locators/Locator.ts

@@ -178,7 +178,7 @@ export abstract class Locator<T> extends EventEmitter {
   /**
    * @internal
    */
-  protected timeout = 30_000;
+  protected _timeout = 30_000;
   #ensureElementIsInTheViewport = true;
   #waitForEnabled = true;
   #waitForStableBoundingBox = true;
@@ -212,12 +212,12 @@ export abstract class Locator<T> extends EventEmitter {
           )
         );
       }
-      if (this.timeout > 0) {
+      if (this._timeout > 0) {
         candidates.push(
-          timer(this.timeout).pipe(
+          timer(this._timeout).pipe(
             map(() => {
               throw new TimeoutError(
-                `Timed out after waiting ${this.timeout}ms`
+                `Timed out after waiting ${this._timeout}ms`
               );
             })
           )
@@ -230,6 +230,11 @@ export abstract class Locator<T> extends EventEmitter {
     },
   };
 
+  // Determines when the locator will timeout for actions.
+  get timeout(): number {
+    return this._timeout;
+  }
+
   override on<K extends keyof LocatorEventObject>(
     eventName: K,
     handler: (event: LocatorEventObject[K]) => void
@@ -251,48 +256,53 @@ export abstract class Locator<T> extends EventEmitter {
     return super.off(eventName, handler);
   }
 
-  setTimeout(timeout: number): this {
+  setTimeout(timeout: number): Locator<T> {
-    this.timeout = timeout;
+    const locator = this._clone();
-    return this;
+    locator._timeout = timeout;
+    return locator;
   }
 
   setVisibility<NodeType extends Node>(
     this: Locator<NodeType>,
     visibility: VisibilityOption
   ): Locator<NodeType> {
-    this.visibility = visibility;
+    const locator = this._clone();
-    return this;
+    locator.visibility = visibility;
+    return locator;
   }
 
   setWaitForEnabled<NodeType extends Node>(
     this: Locator<NodeType>,
     value: boolean
   ): Locator<NodeType> {
-    this.#waitForEnabled = value;
+    const locator = this._clone();
-    return this;
+    locator.#waitForEnabled = value;
+    return locator;
   }
 
   setEnsureElementIsInTheViewport<ElementType extends Element>(
     this: Locator<ElementType>,
     value: boolean
   ): Locator<ElementType> {
-    this.#ensureElementIsInTheViewport = value;
+    const locator = this._clone();
-    return this;
+    locator.#ensureElementIsInTheViewport = value;
+    return locator;
   }
 
   setWaitForStableBoundingBox<ElementType extends Element>(
     this: Locator<ElementType>,
     value: boolean
   ): Locator<ElementType> {
-    this.#waitForStableBoundingBox = value;
+    const locator = this._clone();
-    return this;
+    locator.#waitForStableBoundingBox = value;
+    return locator;
   }
 
   /**
    * @internal
    */
-  copyOptions(locator: Locator<any>): this {
+  copyOptions<T>(locator: Locator<T>): this {
-    this.timeout = locator.timeout;
+    this._timeout = locator._timeout;
     this.visibility = locator.visibility;
     this.#waitForEnabled = locator.#waitForEnabled;
     this.#ensureElementIsInTheViewport = locator.#ensureElementIsInTheViewport;
@@ -320,7 +330,7 @@ export abstract class Locator<T> extends EventEmitter {
           return true;
         },
         {
-          timeout: this.timeout,
+          timeout: this._timeout,
           signal,
         },
         handle
@@ -632,11 +642,23 @@ export abstract class Locator<T> extends EventEmitter {
     );
   }
 
+  /**
+   * @internal
+   */
+  abstract _clone(): Locator<T>;
+
   /**
    * @internal
    */
   abstract _wait(options?: Readonly<ActionOptions>): Observable<HandleFor<T>>;
 
+  /**
+   * Clones the locator.
+   */
+  clone(): Locator<T> {
+    return this._clone();
+  }
+
   /**
    * Waits for the locator to get the serialized value from the page.
    *
@@ -663,7 +685,7 @@ export abstract class Locator<T> extends EventEmitter {
    * @public
    */
   map<To>(mapper: Mapper<T, To>): Locator<To> {
-    return new MappedLocator(this, mapper);
+    return new MappedLocator(this._clone(), mapper);
   }
 
   /**
@@ -674,7 +696,7 @@ export abstract class Locator<T> extends EventEmitter {
    * @public
    */
   filter<S extends T>(predicate: Predicate<T, S>): Locator<S> {
-    return new FilteredLocator(this, predicate);
+    return new FilteredLocator(this._clone(), predicate);
   }
 
   click<ElementType extends Element>(

packages/puppeteer-core/src/api/locators/MappedLocator.ts

@@ -36,6 +36,12 @@ export class MappedLocator<From, To> extends DelegatedLocator<From, To> {
     this.#mapper = mapper;
   }
 
+  override _clone(): MappedLocator<From, To> {
+    return new MappedLocator(this.delegate.clone(), this.#mapper).copyOptions(
+      this
+    );
+  }
+
   override _wait(options?: Readonly<ActionOptions>): Observable<HandleFor<To>> {
     return this.delegate._wait(options).pipe(
       mergeMap(handle => {

packages/puppeteer-core/src/api/locators/NodeLocator.ts

@@ -90,13 +90,19 @@ export class NodeLocator<T extends Node> extends Locator<T> {
     })().pipe(first(identity), retry({delay: RETRY_DELAY}), ignoreElements());
   };
 
-  _wait(options?: Readonly<ActionOptions>): Observable<HandleFor<T>> {
+  override _clone(): NodeLocator<T> {
+    return new NodeLocator<T>(this.#pageOrFrame, this.#selector).copyOptions(
+      this
+    );
+  }
+
+  override _wait(options?: Readonly<ActionOptions>): Observable<HandleFor<T>> {
     const signal = options?.signal;
     return defer(() => {
       return from(
         this.#pageOrFrame.waitForSelector(this.#selector, {
           visible: false,
-          timeout: this.timeout,
+          timeout: this._timeout,
           signal,
         }) as Promise<HandleFor<T> | null>
       );

packages/puppeteer-core/src/api/locators/RaceLocator.ts

@@ -53,6 +53,14 @@ export class RaceLocator<T> extends Locator<T> {
     this.#locators = locators;
   }
 
+  override _clone(): RaceLocator<T> {
+    return new RaceLocator<T>(
+      this.#locators.map(locator => {
+        return locator.clone();
+      })
+    ).copyOptions(this);
+  }
+
   override _wait(options?: Readonly<ActionOptions>): Observable<HandleFor<T>> {
     return race(
       ...this.#locators.map(locator => {

test/src/locator.spec.ts

@@ -647,4 +647,29 @@ describe('Locator', function () {
       await page.locator('div').wait();
     });
   });
+
+  describe('Locator.prototype.clone', () => {
+    it('should work', async () => {
+      const {page} = await getTestState();
+      const locator = page.locator('div');
+      const clone = locator.clone();
+      expect(locator).not.toStrictEqual(clone);
+    });
+    it('should work internally with delegated locators', async () => {
+      const {page} = await getTestState();
+      const locator = page.locator('div');
+      const delegatedLocators = [
+        locator.map(div => {
+          return div.textContent;
+        }),
+        locator.filter(div => {
+          return div.textContent?.length === 0;
+        }),
+      ];
+      for (let delegatedLocator of delegatedLocators) {
+        delegatedLocator = delegatedLocator.setTimeout(500);
+        expect(delegatedLocator.timeout).not.toStrictEqual(locator.timeout);
+      }
+    });
+  });
 });