ExecutionContext.ts

/**
 * Copyright 2017 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import {Protocol} from 'devtools-protocol';
import {assert} from './assert.js';
import {CDPSession} from './Connection.js';
import {DOMWorld} from './DOMWorld.js';
import {ElementHandle} from './ElementHandle.js';
import {Frame} from './FrameManager.js';
import {JSHandle} from './JSHandle.js';
import {EvaluateFunc, HandleFor} from './types.js';
import {
  getExceptionMessage,
  isString,
  valueFromRemoteObject,
  createJSHandle,
} from './util.js';

/**
 * @public
 */
export const EVALUATION_SCRIPT_URL = 'pptr://__puppeteer_evaluation_script__';
const SOURCE_URL_REGEX = /^[\040\t]*\/\/[@#] sourceURL=\s*(\S*?)\s*$/m;

/**
 * This class represents a context for JavaScript execution. A [Page] might have
 * many execution contexts:
 * - each
 *   {@link https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe |
 *   frame } has "default" execution context that is always created after frame is
 *   attached to DOM. This context is returned by the
 *   {@link Frame.executionContext} method.
 * - {@link https://developer.chrome.com/extensions | Extension}'s content scripts
 *   create additional execution contexts.
 *
 * Besides pages, execution contexts can be found in
 * {@link https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API |
 * workers }.
 *
 * @public
 */
export class ExecutionContext {
  /**
   * @internal
   */
  _client: CDPSession;
  /**
   * @internal
   */
  _world?: DOMWorld;
  /**
   * @internal
   */
  _contextId: number;
  /**
   * @internal
   */
  _contextName: string;

  /**
   * @internal
   */
  constructor(
    client: CDPSession,
    contextPayload: Protocol.Runtime.ExecutionContextDescription,
    world?: DOMWorld
  ) {
    this._client = client;
    this._world = world;
    this._contextId = contextPayload.id;
    this._contextName = contextPayload.name;
  }

  /**
   * @remarks
   *
   * Not every execution context is associated with a frame. For
   * example, workers and extensions have execution contexts that are not
   * associated with frames.
   *
   * @returns The frame associated with this execution context.
   */
  frame(): Frame | null {
    return this._world ? this._world.frame() : null;
  }

  /**
   * @remarks
   * If the function passed to the `executionContext.evaluate` returns a
   * Promise, then `executionContext.evaluate` would wait for the promise to
   * resolve and return its value. If the function passed to the
   * `executionContext.evaluate` returns a non-serializable value, then
   * `executionContext.evaluate` resolves to `undefined`. DevTools Protocol also
   * supports transferring some additional values that are not serializable by
   * `JSON`: `-0`, `NaN`, `Infinity`, `-Infinity`, and bigint literals.
   *
   *
   * @example
   * ```ts
   * const executionContext = await page.mainFrame().executionContext();
   * const result = await executionContext.evaluate(() => Promise.resolve(8 * 7))* ;
   * console.log(result); // prints "56"
   * ```
   *
   * @example
   * A string can also be passed in instead of a function.
   *
   * ```ts
   * console.log(await executionContext.evaluate('1 + 2')); // prints "3"
   * ```
   *
   * @example
   * {@link JSHandle} instances can be passed as arguments to the
   * `executionContext.* evaluate`:
   * ```ts
   * const oneHandle = await executionContext.evaluateHandle(() => 1);
   * const twoHandle = await executionContext.evaluateHandle(() => 2);
   * const result = await executionContext.evaluate(
   *    (a, b) => a + b, oneHandle, * twoHandle
   * );
   * await oneHandle.dispose();
   * await twoHandle.dispose();
   * console.log(result); // prints '3'.
   * ```
   * @param pageFunction - a function to be evaluated in the `executionContext`
   * @param args - argument to pass to the page function
   *
   * @returns A promise that resolves to the return value of the given function.
   */
  async evaluate<
    Params extends unknown[],
    Func extends EvaluateFunc<Params> = EvaluateFunc<Params>
  >(
    pageFunction: Func | string,
    ...args: Params
  ): Promise<Awaited<ReturnType<Func>>> {
    return await this.#evaluate(true, pageFunction, ...args);
  }

  /**
   * @remarks
   * The only difference between `executionContext.evaluate` and
   * `executionContext.evaluateHandle` is that `executionContext.evaluateHandle`
   * returns an in-page object (a {@link JSHandle}).
   * If the function passed to the `executionContext.evaluateHandle` returns a
   * Promise, then `executionContext.evaluateHandle` would wait for the
   * promise to resolve and return its value.
   *
   * @example
   * ```ts
   * const context = await page.mainFrame().executionContext();
   * const aHandle = await context.evaluateHandle(() => Promise.resolve(self));
   * aHandle; // Handle for the global object.
   * ```
   *
   * @example
   * A string can also be passed in instead of a function.
   *
   * ```ts
   * // Handle for the '3' * object.
   * const aHandle = await context.evaluateHandle('1 + 2');
   * ```
   *
   * @example
   * JSHandle instances can be passed as arguments
   * to the `executionContext.* evaluateHandle`:
   *
   * ```ts
   * const aHandle = await context.evaluateHandle(() => document.body);
   * const resultHandle = await context.evaluateHandle(body => body.innerHTML, * aHandle);
   * console.log(await resultHandle.jsonValue()); // prints body's innerHTML
   * await aHandle.dispose();
   * await resultHandle.dispose();
   * ```
   *
   * @param pageFunction - a function to be evaluated in the `executionContext`
   * @param args - argument to pass to the page function
   *
   * @returns A promise that resolves to the return value of the given function
   * as an in-page object (a {@link JSHandle}).
   */
  async evaluateHandle<
    Params extends unknown[],
    Func extends EvaluateFunc<Params> = EvaluateFunc<Params>
  >(
    pageFunction: Func | string,
    ...args: Params
  ): Promise<HandleFor<Awaited<ReturnType<Func>>>> {
    return this.#evaluate(false, pageFunction, ...args);
  }

  async #evaluate<
    Params extends unknown[],
    Func extends EvaluateFunc<Params> = EvaluateFunc<Params>
  >(
    returnByValue: true,
    pageFunction: Func | string,
    ...args: Params
  ): Promise<Awaited<ReturnType<Func>>>;
  async #evaluate<
    Params extends unknown[],
    Func extends EvaluateFunc<Params> = EvaluateFunc<Params>
  >(
    returnByValue: false,
    pageFunction: Func | string,
    ...args: Params
  ): Promise<HandleFor<Awaited<ReturnType<Func>>>>;
  async #evaluate<
    Params extends unknown[],
    Func extends EvaluateFunc<Params> = EvaluateFunc<Params>
  >(
    returnByValue: boolean,
    pageFunction: Func | string,
    ...args: Params
  ): Promise<HandleFor<Awaited<ReturnType<Func>>> | Awaited<ReturnType<Func>>> {
    const suffix = `//# sourceURL=${EVALUATION_SCRIPT_URL}`;

    if (isString(pageFunction)) {
      const contextId = this._contextId;
      const expression = pageFunction;
      const expressionWithSourceUrl = SOURCE_URL_REGEX.test(expression)
        ? expression
        : expression + '\n' + suffix;

      const {exceptionDetails, result: remoteObject} = await this._client
        .send('Runtime.evaluate', {
          expression: expressionWithSourceUrl,
          contextId,
          returnByValue,
          awaitPromise: true,
          userGesture: true,
        })
        .catch(rewriteError);

      if (exceptionDetails) {
        throw new Error(
          'Evaluation failed: ' + getExceptionMessage(exceptionDetails)
        );
      }

      return returnByValue
        ? valueFromRemoteObject(remoteObject)
        : createJSHandle(this, remoteObject);
    }

    if (typeof pageFunction !== 'function') {
      throw new Error(
        `Expected to get |string| or |function| as the first argument, but got "${pageFunction}" instead.`
      );
    }

    let functionText = pageFunction.toString();
    try {
      new Function('(' + functionText + ')');
    } catch (error) {
      // This means we might have a function shorthand. Try another
      // time prefixing 'function '.
      if (functionText.startsWith('async ')) {
        functionText =
          'async function ' + functionText.substring('async '.length);
      } else {
        functionText = 'function ' + functionText;
      }
      try {
        new Function('(' + functionText + ')');
      } catch (error) {
        // We tried hard to serialize, but there's a weird beast here.
        throw new Error('Passed function is not well-serializable!');
      }
    }
    let callFunctionOnPromise;
    try {
      callFunctionOnPromise = this._client.send('Runtime.callFunctionOn', {
        functionDeclaration: functionText + '\n' + suffix + '\n',
        executionContextId: this._contextId,
        arguments: args.map(convertArgument.bind(this)),
        returnByValue,
        awaitPromise: true,
        userGesture: true,
      });
    } catch (error) {
      if (
        error instanceof TypeError &&
        error.message.startsWith('Converting circular structure to JSON')
      ) {
        error.message += ' Recursive objects are not allowed.';
      }
      throw error;
    }
    const {exceptionDetails, result: remoteObject} =
      await callFunctionOnPromise.catch(rewriteError);
    if (exceptionDetails) {
      throw new Error(
        'Evaluation failed: ' + getExceptionMessage(exceptionDetails)
      );
    }
    return returnByValue
      ? valueFromRemoteObject(remoteObject)
      : createJSHandle(this, remoteObject);

    function convertArgument(
      this: ExecutionContext,
      arg: unknown
    ): Protocol.Runtime.CallArgument {
      if (typeof arg === 'bigint') {
        // eslint-disable-line valid-typeof
        return {unserializableValue: `${arg.toString()}n`};
      }
      if (Object.is(arg, -0)) {
        return {unserializableValue: '-0'};
      }
      if (Object.is(arg, Infinity)) {
        return {unserializableValue: 'Infinity'};
      }
      if (Object.is(arg, -Infinity)) {
        return {unserializableValue: '-Infinity'};
      }
      if (Object.is(arg, NaN)) {
        return {unserializableValue: 'NaN'};
      }
      const objectHandle = arg && arg instanceof JSHandle ? arg : null;
      if (objectHandle) {
        if (objectHandle._context !== this) {
          throw new Error(
            'JSHandles can be evaluated only in the context they were created!'
          );
        }
        if (objectHandle._disposed) {
          throw new Error('JSHandle is disposed!');
        }
        if (objectHandle._remoteObject.unserializableValue) {
          return {
            unserializableValue: objectHandle._remoteObject.unserializableValue,
          };
        }
        if (!objectHandle._remoteObject.objectId) {
          return {value: objectHandle._remoteObject.value};
        }
        return {objectId: objectHandle._remoteObject.objectId};
      }
      return {value: arg};
    }

    function rewriteError(error: Error): Protocol.Runtime.EvaluateResponse {
      if (error.message.includes('Object reference chain is too long')) {
        return {result: {type: 'undefined'}};
      }
      if (error.message.includes("Object couldn't be returned by value")) {
        return {result: {type: 'undefined'}};
      }

      if (
        error.message.endsWith('Cannot find context with specified id') ||
        error.message.endsWith('Inspected target navigated or closed')
      ) {
        throw new Error(
          'Execution context was destroyed, most likely because of a navigation.'
        );
      }
      throw error;
    }
  }

  /**
   * This method iterates the JavaScript heap and finds all the objects with the
   * given prototype.
   * @remarks
   * @example
   * ```ts
   * // Create a Map object
   * await page.evaluate(() => window.map = new Map());
   * // Get a handle to the Map object prototype
   * const mapPrototype = await page.evaluateHandle(() => Map.prototype);
   * // Query all map instances into an array
   * const mapInstances = await page.queryObjects(mapPrototype);
   * // Count amount of map objects in heap
   * const count = await page.evaluate(maps => maps.length, mapInstances);
   * await mapInstances.dispose();
   * await mapPrototype.dispose();
   * ```
   *
   * @param prototypeHandle - a handle to the object prototype
   *
   * @returns A handle to an array of objects with the given prototype.
   */
  async queryObjects<Prototype>(
    prototypeHandle: JSHandle<Prototype>
  ): Promise<HandleFor<Prototype[]>> {
    assert(!prototypeHandle._disposed, 'Prototype JSHandle is disposed!');
    assert(
      prototypeHandle._remoteObject.objectId,
      'Prototype JSHandle must not be referencing primitive value'
    );
    const response = await this._client.send('Runtime.queryObjects', {
      prototypeObjectId: prototypeHandle._remoteObject.objectId,
    });
    return createJSHandle(this, response.objects) as HandleFor<Prototype[]>;
  }

  /**
   * @internal
   */
  async _adoptBackendNodeId(
    backendNodeId?: Protocol.DOM.BackendNodeId
  ): Promise<ElementHandle<Node>> {
    const {object} = await this._client.send('DOM.resolveNode', {
      backendNodeId: backendNodeId,
      executionContextId: this._contextId,
    });
    return createJSHandle(this, object) as ElementHandle<Node>;
  }

  /**
   * @internal
   */
  async _adoptElementHandle<T extends ElementHandle<Node>>(
    elementHandle: T
  ): Promise<T> {
    assert(
      elementHandle.executionContext() !== this,
      'Cannot adopt handle that already belongs to this execution context'
    );
    assert(this._world, 'Cannot adopt handle without DOMWorld');
    const nodeInfo = await this._client.send('DOM.describeNode', {
      objectId: elementHandle._remoteObject.objectId,
    });
    return (await this._adoptBackendNodeId(nodeInfo.node.backendNodeId)) as T;
  }
}