new_audit: add no-unload-listeners audit (#11085)

GoogleChrome · Jul 21, 2020 · ca5b892 · ca5b892
1 parent 439596e
commit ca5b892
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Showing 12 changed files with 416 additions and 5 deletions.
diff --git a/lighthouse-cli/test/cli/__snapshots__/index-test.js.snap b/lighthouse-cli/test/cli/__snapshots__/index-test.js.snap
@@ -159,6 +159,9 @@ Object {
     Object {
       "path": "long-tasks",
     },
+    Object {
+      "path": "no-unload-listeners",
+    },
     Object {
       "path": "manual/pwa-cross-browser",
     },
@@ -747,6 +750,11 @@ Object {
           "id": "charset",
           "weight": 1,
         },
+        Object {
+          "group": "best-practices-general",
+          "id": "no-unload-listeners",
+          "weight": 1,
+        },
         Object {
           "group": "best-practices-general",
           "id": "appcache-manifest",
@@ -1323,6 +1331,9 @@ Object {
         Object {
           "path": "main-document-content",
         },
+        Object {
+          "path": "global-listeners",
+        },
         Object {
           "path": "dobetterweb/appcache",
         },

diff --git a/lighthouse-cli/test/fixtures/dobetterweb/dbw_tester.html b/lighthouse-cli/test/fixtures/dobetterweb/dbw_tester.html
@@ -383,6 +383,12 @@ <h2>Do better web tester page</h2>
   document.body.appendChild(img); // PASS
 }
 
+function noUnloadListenersTest() {
+  window.addEventListener('unload', () => {
+    console.log('unload on unload');
+  });
+}
+
 // Figure out which tests to fun.
 const params = new URLSearchParams(location.search);
 if (location.search === '') {
@@ -398,6 +404,7 @@ <h2>Do better web tester page</h2>
   deprecationsTest();
   passwordInputsCanBePastedIntoTest();
   isOnHttps();
+  noUnloadListenersTest();
 } else {
   if (params.has('documentWrite')) {
     documentWriteTest();

diff --git a/lighthouse-cli/test/smokehouse/test-definitions/dobetterweb/dbw-expectations.js b/lighthouse-cli/test/smokehouse/test-definitions/dobetterweb/dbw-expectations.js
@@ -197,6 +197,12 @@ const expectations = [
           },
         },
       ],
+      GlobalListeners: [{
+        type: 'unload',
+        scriptId: /^\d+$/,
+        lineNumber: '>300',
+        columnNumber: '>30',
+      }],
     },
     lhr: {
       requestedUrl: 'http://localhost:10200/dobetterweb/dbw_tester.html',
@@ -413,6 +419,20 @@ const expectations = [
             ],
           },
         },
+        'no-unload-listeners': {
+          score: 0,
+          details: {
+            items: [{
+              source: {
+                type: 'source-location',
+                url: 'http://localhost:10200/dobetterweb/dbw_tester.html',
+                urlProvider: 'network',
+                line: '>300',
+                column: '>30',
+              },
+            }],
+          },
+        },
       },
     },
   },

diff --git a/lighthouse-core/audits/no-unload-listeners.js b/lighthouse-core/audits/no-unload-listeners.js
@@ -0,0 +1,94 @@
+/**
+ * @license Copyright 2020 The Lighthouse Authors. 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';
+
+const Audit = require('./audit.js');
+const i18n = require('./../lib/i18n/i18n.js');
+
+const UIStrings = {
+  /** Descriptive title of a Lighthouse audit that checks if a web page has 'unload' event listeners and finds none. */
+  title: 'Avoids `unload` event listeners',
+  /** Descriptive title of a Lighthouse audit that checks if a web page has 'unload' event listeners and finds that it is using them. */
+  failureTitle: 'Registers an `unload` listener',
+  /** Description of a Lighthouse audit that tells the user why pages should not use the 'unload' event. This is displayed after a user expands the section to see more. 'Learn More' becomes link text to additional documentation. */
+  description: 'The `unload` event does not fire reliably and listening for it can prevent browser optimizations like the Back-Forward Cache. Consider using the `pagehide` or `visibilitychange` events instead. [Learn More](https://developers.google.com/web/updates/2018/07/page-lifecycle-api#the-unload-event)',
+};
+
+const str_ = i18n.createMessageInstanceIdFn(__filename, UIStrings);
+
+class NoUnloadListeners extends Audit {
+  /**
+   * @return {LH.Audit.Meta}
+   */
+  static get meta() {
+    return {
+      id: 'no-unload-listeners',
+      title: str_(UIStrings.title),
+      failureTitle: str_(UIStrings.failureTitle),
+      description: str_(UIStrings.description),
+      requiredArtifacts: ['GlobalListeners', 'JsUsage'],
+    };
+  }
+
+  /**
+   * @param {LH.Artifacts} artifacts
+   * @return {LH.Audit.Product}
+   */
+  static audit(artifacts) {
+    const unloadListeners = artifacts.GlobalListeners.filter(l => l.type === 'unload');
+    if (!unloadListeners.length) {
+      return {
+        score: 1,
+      };
+    }
+
+    /** @type {LH.Audit.Details.Table['headings']} */
+    const headings = [
+      {key: 'source', itemType: 'source-location', text: str_(i18n.UIStrings.columnURL)},
+    ];
+
+    // Look up scriptId to script URL via the JsUsage artifact.
+    /** @type {Array<[string, string]>} */
+    const scriptIdToUrlEntries = Object.values(artifacts.JsUsage)
+      .reduce((acc, usage) => acc.concat(usage), []) // single-level arr.flat().
+      .map(usage => [usage.scriptId, usage.url]);
+    const scriptIdToUrl = new Map(scriptIdToUrlEntries);
+
+    /** @type {Array<{source: LH.Audit.Details.ItemValue}>} */
+    const tableItems = unloadListeners.map(listener => {
+      const url = scriptIdToUrl.get(listener.scriptId);
+
+      // If we can't find a url, still show something so the user can manually
+      // look for where an `unload` handler is being created.
+      if (!url) {
+        return {
+          source: {
+            type: 'url',
+            value: '(unknown)',
+          },
+        };
+      }
+
+      return {
+        source: {
+          type: 'source-location',
+          url,
+          urlProvider: 'network',
+          line: listener.lineNumber,
+          column: listener.columnNumber,
+        },
+      };
+    });
+
+    return {
+      score: 0,
+      details: Audit.makeTableDetails(headings, tableItems),
+    };
+  }
+}
+
+module.exports = NoUnloadListeners;
+module.exports.UIStrings = UIStrings;
diff --git a/lighthouse-core/config/default-config.js b/lighthouse-core/config/default-config.js
@@ -147,6 +147,7 @@ const defaultConfig = {
       'script-elements',
       'iframe-elements',
       'main-document-content',
+      'global-listeners',
       'dobetterweb/appcache',
       'dobetterweb/doctype',
       'dobetterweb/domstats',
@@ -236,6 +237,7 @@ const defaultConfig = {
     'largest-contentful-paint-element',
     'layout-shift-elements',
     'long-tasks',
+    'no-unload-listeners',
     'manual/pwa-cross-browser',
     'manual/pwa-page-transitions',
     'manual/pwa-each-page-has-url',
@@ -556,6 +558,7 @@ const defaultConfig = {
         {id: 'doctype', weight: 1, group: 'best-practices-browser-compat'},
         {id: 'charset', weight: 1, group: 'best-practices-browser-compat'},
         // General Group
+        {id: 'no-unload-listeners', weight: 1, group: 'best-practices-general'},
         {id: 'appcache-manifest', weight: 1, group: 'best-practices-general'},
         {id: 'js-libraries', weight: 0, group: 'best-practices-general'},
         {id: 'deprecations', weight: 1, group: 'best-practices-general'},

diff --git a/lighthouse-core/gather/gatherers/global-listeners.js b/lighthouse-core/gather/gatherers/global-listeners.js
@@ -0,0 +1,60 @@
+/**
+ * @license Copyright 2020 The Lighthouse Authors. 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';
+
+/**
+ * @fileoverview
+ * A gatherer to collect information about the event listeners registered on the
+ * global object. For now, the scope is narrowed to events that occur on and
+ * around page unload, but this can be expanded in the future.
+ */
+
+const Gatherer = require('./gatherer.js');
+
+class GlobalListeners extends Gatherer {
+  /**
+   * @param {LH.Crdp.DOMDebugger.EventListener} listener
+   * @return {listener is {type: 'pagehide'|'unload'|'visibilitychange'} & LH.Crdp.DOMDebugger.EventListener}
+   */
+  static _filterForAllowlistedTypes(listener) {
+    return listener.type === 'pagehide' ||
+      listener.type === 'unload' ||
+      listener.type === 'visibilitychange';
+  }
+
+  /**
+   * @param {LH.Gatherer.PassContext} passContext
+   * @return {Promise<LH.Artifacts['GlobalListeners']>}
+   */
+  async afterPass(passContext) {
+    const driver = passContext.driver;
+
+    // Get a RemoteObject handle to `window`.
+    const {result: {objectId}} = await driver.sendCommand('Runtime.evaluate', {
+      expression: 'window',
+      returnByValue: false,
+    });
+    if (!objectId) {
+      throw new Error('Error fetching information about the global object');
+    }
+
+    // And get all its listeners of interest.
+    const {listeners} = await driver.sendCommand('DOMDebugger.getEventListeners', {objectId});
+    return listeners
+      .filter(GlobalListeners._filterForAllowlistedTypes)
+      .map(listener => {
+        const {type, scriptId, lineNumber, columnNumber} = listener;
+        return {
+          type,
+          scriptId,
+          lineNumber,
+          columnNumber,
+        };
+      });
+  }
+}
+
+module.exports = GlobalListeners;
diff --git a/lighthouse-core/lib/i18n/locales/en-US.json b/lighthouse-core/lib/i18n/locales/en-US.json
@@ -959,6 +959,15 @@
   "lighthouse-core/audits/network-server-latency.js | title": {
     "message": "Server Backend Latencies"
   },
+  "lighthouse-core/audits/no-unload-listeners.js | description": {
+    "message": "The `unload` event does not fire reliably and listening for it can prevent browser optimizations like the Back-Forward Cache. Consider using the `pagehide` or `visibilitychange` events instead. [Learn More](https://developers.google.com/web/updates/2018/07/page-lifecycle-api#the-unload-event)"
+  },
+  "lighthouse-core/audits/no-unload-listeners.js | failureTitle": {
+    "message": "Registers an `unload` listener"
+  },
+  "lighthouse-core/audits/no-unload-listeners.js | title": {
+    "message": "Avoids `unload` event listeners"
+  },
   "lighthouse-core/audits/offline-start-url.js | description": {
     "message": "A service worker enables your web app to be reliable in unpredictable network conditions. [Learn more](https://web.dev/offline-start-url/)."
   },

diff --git a/lighthouse-core/lib/i18n/locales/en-XL.json b/lighthouse-core/lib/i18n/locales/en-XL.json
@@ -959,6 +959,15 @@
   "lighthouse-core/audits/network-server-latency.js | title": {
     "message": "Ŝér̂v́êŕ B̂áĉḱêńd̂ Ĺât́êńĉíêś"
   },
+  "lighthouse-core/audits/no-unload-listeners.js | description": {
+    "message": "T̂h́ê `unload` év̂én̂t́ d̂óêś n̂ót̂ f́îŕê ŕêĺîáb̂ĺŷ án̂d́ l̂íŝt́êńîńĝ f́ôŕ ît́ ĉán̂ ṕr̂év̂én̂t́ b̂ŕôẃŝér̂ óp̂t́îḿîźât́îón̂ś l̂ík̂é t̂h́ê B́âćk̂-F́ôŕŵár̂d́ Ĉáĉh́ê. Ćôńŝíd̂ér̂ úŝín̂ǵ t̂h́ê `pagehide` ór̂ `visibilitychange` év̂én̂t́ŝ ín̂śt̂éâd́. [L̂éâŕn̂ Ḿôŕê](https://developers.google.com/web/updates/2018/07/page-lifecycle-api#the-unload-event)"
+  },
+  "lighthouse-core/audits/no-unload-listeners.js | failureTitle": {
+    "message": "R̂éĝíŝt́êŕŝ án̂ `unload` ĺîśt̂én̂ér̂"
+  },
+  "lighthouse-core/audits/no-unload-listeners.js | title": {
+    "message": "Âv́ôíd̂ś `unload` êv́êńt̂ ĺîśt̂én̂ér̂ś"
+  },
   "lighthouse-core/audits/offline-start-url.js | description": {
     "message": "Â śêŕv̂íĉé ŵór̂ḱêŕ êńâb́l̂éŝ ýôúr̂ ẃêb́ âṕp̂ t́ô b́ê ŕêĺîáb̂ĺê ín̂ ún̂ṕr̂éd̂íĉt́âb́l̂é n̂ét̂ẃôŕk̂ ćôńd̂ít̂íôńŝ. [Ĺêár̂ń m̂ór̂é](https://web.dev/offline-start-url/)."
   },

diff --git a/lighthouse-core/test/audits/no-unload-listeners-test.js b/lighthouse-core/test/audits/no-unload-listeners-test.js
@@ -0,0 +1,77 @@
+/**
+ * @license Copyright 2020 The Lighthouse Authors. 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';
+
+const NoUnloadListeners = require('../../audits/no-unload-listeners.js');
+
+/* eslint-env jest */
+
+const testJsUsage = {
+  'https://example.com/1.js': [
+    {scriptId: '12', url: 'https://example.com/1.js', functions: []},
+    {scriptId: '13', url: 'https://example.com/1.js', functions: []},
+    {scriptId: '16', url: 'https://example.com/1.js', functions: []},
+    {scriptId: '17', url: 'https://example.com/1.js', functions: []},
+  ],
+  'https://example.com/2.js': [
+    {scriptId: '22', url: 'https://example.com/2.js', functions: []},
+    {scriptId: '23', url: 'https://example.com/2.js', functions: []},
+    {scriptId: '26', url: 'https://example.com/2.js', functions: []},
+    {scriptId: '27', url: 'https://example.com/2.js', functions: []},
+  ],
+};
+
+describe('No Unload Listeners', () => {
+  it('passes when there were no listeners', () => {
+    const artifacts = {JsUsage: testJsUsage, GlobalListeners: []};
+    const result = NoUnloadListeners.audit(artifacts);
+    expect(result).toEqual({score: 1});
+  });
+
+  it('passes when there were no `unload` listeners', () => {
+    const GlobalListeners = [{
+      type: 'DOMContentLoaded', scriptId: '12', lineNumber: 5, columnNumber: 0,
+    }];
+    const artifacts = {JsUsage: testJsUsage, GlobalListeners};
+    const result = NoUnloadListeners.audit(artifacts);
+    expect(result).toEqual({score: 1});
+  });
+
+  it('fails when there are unload listeners and matches them to script locations', () => {
+    const GlobalListeners = [
+      {type: 'unload', scriptId: '16', lineNumber: 10, columnNumber: 30},
+      {type: 'unload', scriptId: '23', lineNumber: 0, columnNumber: 0},
+    ];
+    const artifacts = {JsUsage: testJsUsage, GlobalListeners};
+    const result = NoUnloadListeners.audit(artifacts);
+    expect(result.score).toEqual(0);
+    expect(result.details.items).toMatchObject([
+      {
+        source: {type: 'source-location', url: 'https://example.com/1.js', urlProvider: 'network', line: 10, column: 30},
+      }, {
+        source: {type: 'source-location', url: 'https://example.com/2.js', urlProvider: 'network', line: 0, column: 0},
+      },
+    ]);
+  });
+
+  it('fails when there are unload listeners and has a fallback if script URL is not found', () => {
+    const GlobalListeners = [
+      {type: 'DOMContentLoaded', scriptId: '12', lineNumber: 5, columnNumber: 0},
+      {type: 'unload', scriptId: 'notascriptid', lineNumber: 10, columnNumber: 30},
+      {type: 'unload', scriptId: '22', lineNumber: 1, columnNumber: 100},
+    ];
+    const artifacts = {JsUsage: testJsUsage, GlobalListeners};
+    const result = NoUnloadListeners.audit(artifacts);
+    expect(result.score).toEqual(0);
+    expect(result.details.items).toMatchObject([
+      {
+        source: {type: 'url', value: '(unknown)'},
+      }, {
+        source: {type: 'source-location', url: 'https://example.com/2.js', urlProvider: 'network', line: 1, column: 100},
+      },
+    ]);
+  });
+});