lighthouse/core/gather/driver/dom.js

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

/**
 * @license
 * Copyright 2021 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @param {Error} err
 * @return {undefined}
 */
function handlePotentialMissingNodeError(err) {
  if (
    /No node.*found/.test(err.message) ||
    /Node.*does not belong to the document/.test(err.message)
  ) {
    return undefined;
  }
  throw err;
}

/**
 * Resolves a backend node ID (from a trace event, protocol, etc) to the object ID for use with
 * `Runtime.callFunctionOn`. `undefined` means the node could not be found.
 *
 * @param {LH.Gatherer.ProtocolSession} session
 * @param {number} backendNodeId
 * @return {Promise<string|undefined>}
 */
async function resolveNodeIdToObjectId(session, backendNodeId) {
  try {
    const resolveNodeResponse = await session.sendCommand('DOM.resolveNode', {backendNodeId});
    return resolveNodeResponse.object.objectId;
  } catch (err) {
    return handlePotentialMissingNodeError(err);
  }
}

/**
 * Resolves a proprietary devtools node path (created from page-function.js) to the object ID for use
 * with `Runtime.callFunctionOn`. `undefined` means the node could not be found.
 * Requires `DOM.getDocument` to have been called since the object's creation or it will always be `undefined`.
 *
 * @param {LH.Gatherer.ProtocolSession} session
 * @param {string} path
 * @return {Promise<string|undefined>}
 */
async function resolveDevtoolsNodePathToObjectId(session, path) {
  try {
    const {nodeId} = await session.sendCommand('DOM.pushNodeByPathToFrontend', {path});
    const {object: {objectId}} = await session.sendCommand('DOM.resolveNode', {nodeId});
    return objectId;
  } catch (err) {
    return handlePotentialMissingNodeError(err);
  }
}

export {resolveNodeIdToObjectId, resolveDevtoolsNodePathToObjectId};