# all files / lighthouse-core/lib/ emulation.js

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     /**
     * @license
     * Copyright 2016 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.
     */
    'use strict';

    /**
     * Nexus 5X metrics adapted from emulated_devices/module.json
     */
    const NEXUS5X_EMULATION_METRICS = {
      mobile: true,
      screenWidth: 412,
      screenHeight: 732,
      width: 412,
      height: 732,
      positionX: 0,
      positionY: 0,
      scale: 1,
      deviceScaleFactor: 2.625,
      fitWindow: false,
      screenOrientation: {
        angle: 0,
        type: 'portraitPrimary'
      }
    };

    const NEXUS5X_USERAGENT = {
      userAgent: 'Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5 Build/MRA58N) AppleWebKit/537.36' +
        '(KHTML, like Gecko) Chrome/52.0.2743.8 Mobile Safari/537.36'
    };

    const TYPICAL_MOBILE_THROTTLING_METRICS = {
      latency: 150, // 150ms
      downloadThroughput: 1.6 * 1024 * 1024 / 8, // 1.6Mbps
      uploadThroughput: 750 * 1024 / 8, // 750Kbps
      offline: false
    };

    function enableNexus5X(driver) {
      /**
       * Finalizes touch emulation by enabling `"ontouchstart" in window` feature detect
       * to work. Messy hack, though copied verbatim from DevTools' emulation/TouchModel.js
       * where it's been working for years. addScriptToEvaluateOnLoad runs before any of the
       * page's JavaScript executes.
       */
      /* eslint-disable no-proto */ /* global window, document */ /* istanbul ignore next */
      const injectedTouchEventsFunction = function() {
        const touchEvents = ['ontouchstart', 'ontouchend', 'ontouchmove', 'ontouchcancel'];
        var recepients = [window.__proto__, document.__proto__];
        for (var i = 0; i < touchEvents.length; ++i) {
          for (var j = 0; j < recepients.length; ++j) {
            if (!(touchEvents[i] in recepients[j])) {
              Object.defineProperty(recepients[j], touchEvents[i], {
                value: null, writable: true, configurable: true, enumerable: true
              });
            }
          }
        }
      };
      /* eslint-enable */

      return Promise.all([
        driver.sendCommand('Emulation.setDeviceMetricsOverride', NEXUS5X_EMULATION_METRICS),
        driver.sendCommand('Network.setUserAgentOverride', NEXUS5X_USERAGENT),
        driver.sendCommand('Emulation.setTouchEmulationEnabled', {
          enabled: true,
          configuration: 'mobile'
        }),
        driver.sendCommand('Page.addScriptToEvaluateOnLoad', {
          scriptSource: '(' + injectedTouchEventsFunction.toString() + ')()'
        })
      ]);
    }

    function enableNetworkThrottling(driver) {
      return driver.sendCommand('Network.emulateNetworkConditions', TYPICAL_MOBILE_THROTTLING_METRICS);
    }

    module.exports = {
      enableNexus5X,
      enableNetworkThrottling
    };