lighthouse/core/gather/gatherers/console-messages.js

Automated auditing, performance metrics, and best practices for the web.

/**
 * @license
 * Copyright 2020 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @fileoverview Gathers all entries logged to the console, including console API calls,
 * exceptions, and browser reports (on violations, interventions, deprecations, etc.).
 */


import BaseGatherer from '../base-gatherer.js';

/**
 * @param {LH.Crdp.Runtime.RemoteObject} obj
 * @return {string}
 */
function remoteObjectToString(obj) {
  if (typeof obj.value !== 'undefined' || obj.type === 'undefined') {
    return String(obj.value);
  }
  if (typeof obj.description === 'string' && obj.description !== obj.className) {
    return obj.description;
  }
  const type = obj.subtype || obj.type;
  const className = obj.className || 'Object';
  // Simulate calling String() on the object.
  return `[${type} ${className}]`;
}

class ConsoleMessages extends BaseGatherer {
  /** @type {LH.Gatherer.GathererMeta} */
  meta = {
    supportedModes: ['timespan', 'navigation'],
  };

  constructor() {
    super();
    /** @type {LH.Artifacts.ConsoleMessage[]} */
    this._logEntries = [];

    this._onConsoleAPICalled = this.onConsoleAPICalled.bind(this);
    this._onExceptionThrown = this.onExceptionThrown.bind(this);
    this._onLogEntryAdded = this.onLogEntry.bind(this);
  }

  /**
   * Handles events for when a script invokes a console API.
   * @param {LH.Crdp.Runtime.ConsoleAPICalledEvent} event
   */
  onConsoleAPICalled(event) {
    const {type} = event;
    if (type !== 'warning' && type !== 'error') {
      // Only gather warnings and errors for brevity.
      return;
    }

    /** @type {LH.Crdp.Runtime.RemoteObject[]} */
    const args = event.args || [];
    const text = args.map(remoteObjectToString).join(' ');
    if (!text && !event.stackTrace) {
      // No useful information from Chrome. Skip.
      return;
    }

    const {url, lineNumber, columnNumber} =
      event.stackTrace?.callFrames[0] || {};
    /** @type {LH.Artifacts.ConsoleMessage} */
    const consoleMessage = {
      eventType: 'consoleAPI',
      source: type === 'warning' ? 'console.warn' : 'console.error',
      level: type,
      text,
      stackTrace: event.stackTrace,
      timestamp: event.timestamp,
      url,
      lineNumber,
      columnNumber,
    };
    this._logEntries.push(consoleMessage);
  }

  /**
   * Handles exception thrown events.
   * @param {LH.Crdp.Runtime.ExceptionThrownEvent} event
   */
  onExceptionThrown(event) {
    const text = event.exceptionDetails.exception ?
          event.exceptionDetails.exception.description : event.exceptionDetails.text;
    if (!text) {
      return;
    }
    /** @type {LH.Artifacts.ConsoleMessage} */
    const consoleMessage = {
      eventType: 'exception',
      source: 'exception',
      level: 'error',
      text,
      stackTrace: event.exceptionDetails.stackTrace,
      timestamp: event.timestamp,
      url: event.exceptionDetails.url,
      scriptId: event.exceptionDetails.scriptId,
      lineNumber: event.exceptionDetails.lineNumber,
      columnNumber: event.exceptionDetails.columnNumber,
    };
    this._logEntries.push(consoleMessage);
  }

  /**
   * Handles browser reports logged to the console, including interventions,
   * deprecations, violations, and more.
   * @param {LH.Crdp.Log.EntryAddedEvent} event
   */
  onLogEntry(event) {
    const {source, level, text, stackTrace, timestamp, url, lineNumber} = event.entry;

    // JS events have a stack trace, which we use to get the column.
    // CSS/HTML events only expose a line number.
    const firstStackFrame = event.entry.stackTrace?.callFrames[0];

    this._logEntries.push({
      eventType: 'protocolLog',
      source,
      level,
      text,
      stackTrace,
      timestamp,
      url,
      scriptId: firstStackFrame?.scriptId,
      lineNumber,
      columnNumber: firstStackFrame?.columnNumber,
    });
  }

  /**
   * @param {LH.Gatherer.Context} passContext
   */
  async startInstrumentation(passContext) {
    const session = passContext.driver.defaultSession;

    session.on('Log.entryAdded', this._onLogEntryAdded);
    await session.sendCommand('Log.enable');
    await session.sendCommand('Log.startViolationsReport', {
      config: [{name: 'discouragedAPIUse', threshold: -1}],
    });

    session.on('Runtime.consoleAPICalled', this._onConsoleAPICalled);
    session.on('Runtime.exceptionThrown', this._onExceptionThrown);
    await session.sendCommand('Runtime.enable');
  }

  /**
   * @param {LH.Gatherer.Context} passContext
   * @return {Promise<void>}
   */
  async stopInstrumentation({driver}) {
    await driver.defaultSession.sendCommand('Log.stopViolationsReport');
    await driver.defaultSession.off('Log.entryAdded', this._onLogEntryAdded);
    await driver.defaultSession.sendCommand('Log.disable');
    await driver.defaultSession.off('Runtime.consoleAPICalled', this._onConsoleAPICalled);
    await driver.defaultSession.off('Runtime.exceptionThrown', this._onExceptionThrown);
    await driver.defaultSession.sendCommand('Runtime.disable');
  }

  /**
   * @return {Promise<LH.Artifacts['ConsoleMessages']>}
   */
  async getArtifact() {
    return this._logEntries;
  }
}

export default ConsoleMessages;