Worker.ts

/**
 * Copyright 2018 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 {EventEmitter} from 'events';
import {debugError} from './helper';
import {ExecutionContext} from './ExecutionContext';
import {JSHandle} from './JSHandle';
import {CDPSession} from './Connection';

type ConsoleAPICalledCallback = (eventType: string, handles: JSHandle[], trace: Protocol.Runtime.StackTrace) => void;
type ExceptionThrownCallback = (details: Protocol.Runtime.ExceptionDetails) => void;
type JSHandleFactory = (obj: Protocol.Runtime.RemoteObject) => JSHandle;

export class Worker extends EventEmitter {
  _client: CDPSession;
  _url: string;
  _executionContextPromise: Promise<ExecutionContext>;
  _executionContextCallback: (value: ExecutionContext) => void;

  constructor(client: CDPSession, url: string, consoleAPICalled: ConsoleAPICalledCallback, exceptionThrown: ExceptionThrownCallback) {
    super();
    this._client = client;
    this._url = url;
    this._executionContextPromise = new Promise<ExecutionContext>(x => this._executionContextCallback = x);

    let jsHandleFactory: JSHandleFactory;
    this._client.once('Runtime.executionContextCreated', async event => {
      // eslint-disable-next-line @typescript-eslint/explicit-function-return-type
      jsHandleFactory = remoteObject => new JSHandle(executionContext, client, remoteObject);
      const executionContext = new ExecutionContext(client, event.context, null);
      this._executionContextCallback(executionContext);
    });

    // This might fail if the target is closed before we recieve all execution contexts.
    this._client.send('Runtime.enable', {}).catch(debugError);
    this._client.on('Runtime.consoleAPICalled', event => consoleAPICalled(event.type, event.args.map(jsHandleFactory), event.stackTrace));
    this._client.on('Runtime.exceptionThrown', exception => exceptionThrown(exception.exceptionDetails));
  }

  url(): string {
    return this._url;
  }

  async executionContext(): Promise<ExecutionContext> {
    return this._executionContextPromise;
  }

  async evaluate<ReturnType extends any>(pageFunction: Function|string, ...args: any[]): Promise<ReturnType> {
    return (await this._executionContextPromise).evaluate<ReturnType>(pageFunction, ...args);
  }

  async evaluateHandle(pageFunction: Function|string, ...args: any[]): Promise<JSHandle> {
    return (await this._executionContextPromise).evaluateHandle(pageFunction, ...args);
  }
}