core(config): enable unused-javascript by default (#9854)

GoogleChrome · Nov 6, 2019 · 713a70a · 713a70a
1 parent 466bd6f
commit 713a70a
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Showing 10 changed files with 79 additions and 23 deletions.
diff --git a/lighthouse-cli/test/cli/__snapshots__/index-test.js.snap b/lighthouse-cli/test/cli/__snapshots__/index-test.js.snap
@@ -321,6 +321,9 @@ Object {
     Object {
       "path": "byte-efficiency/unused-css-rules",
     },
+    Object {
+      "path": "byte-efficiency/unused-javascript",
+    },
     Object {
       "path": "byte-efficiency/uses-webp-images",
     },
@@ -799,6 +802,11 @@ Object {
           "id": "unused-css-rules",
           "weight": 0,
         },
+        Object {
+          "group": "load-opportunities",
+          "id": "unused-javascript",
+          "weight": 0,
+        },
         Object {
           "group": "load-opportunities",
           "id": "uses-optimized-images",
@@ -1169,6 +1177,9 @@ Object {
         Object {
           "path": "css-usage",
         },
+        Object {
+          "path": "js-usage",
+        },
         Object {
           "path": "viewport-dimensions",
         },

diff --git a/lighthouse-core/audits/byte-efficiency/unused-javascript.js b/lighthouse-core/audits/byte-efficiency/unused-javascript.js
@@ -12,7 +12,8 @@ const UIStrings = {
   /** Imperative title of a Lighthouse audit that tells the user to remove JavaScript that is never evaluated during page load. This is displayed in a list of audit titles that Lighthouse generates. */
   title: 'Remove unused JavaScript',
   /** Description of a Lighthouse audit that tells the user *why* they should remove JavaScript that is never needed/evaluated by the browser. This is displayed after a user expands the section to see more. No character length limits. 'Learn More' becomes link text to additional documentation. */
-  description: 'Remove unused JavaScript to reduce bytes consumed by network activity.',
+  description: 'Remove unused JavaScript to reduce bytes consumed by network activity. ' +
+    '[Learn more](https://developers.google.com/web/fundamentals/performance/optimizing-javascript/code-splitting).',
 };
 
 const str_ = i18n.createMessageInstanceIdFn(__filename, UIStrings);

diff --git a/lighthouse-core/config/default-config.js b/lighthouse-core/config/default-config.js
@@ -127,6 +127,7 @@ const defaultConfig = {
     cpuQuietThresholdMs: 1000,
     gatherers: [
       'css-usage',
+      'js-usage',
       'viewport-dimensions',
       'runtime-exceptions',
       'console-messages',
@@ -275,6 +276,7 @@ const defaultConfig = {
     'byte-efficiency/unminified-css',
     'byte-efficiency/unminified-javascript',
     'byte-efficiency/unused-css-rules',
+    'byte-efficiency/unused-javascript',
     'byte-efficiency/uses-webp-images',
     'byte-efficiency/uses-optimized-images',
     'byte-efficiency/uses-text-compression',
@@ -393,6 +395,7 @@ const defaultConfig = {
         {id: 'unminified-css', weight: 0, group: 'load-opportunities'},
         {id: 'unminified-javascript', weight: 0, group: 'load-opportunities'},
         {id: 'unused-css-rules', weight: 0, group: 'load-opportunities'},
+        {id: 'unused-javascript', weight: 0, group: 'load-opportunities'},
         {id: 'uses-optimized-images', weight: 0, group: 'load-opportunities'},
         {id: 'uses-webp-images', weight: 0, group: 'load-opportunities'},
         {id: 'uses-text-compression', weight: 0, group: 'load-opportunities'},

diff --git a/lighthouse-core/config/full-config.js b/lighthouse-core/config/full-config.js
@@ -9,25 +9,6 @@
 const fullConfig = {
   extends: 'lighthouse:default',
   settings: {},
-  passes: [
-    {
-      passName: 'extraPass',
-      gatherers: [
-        'js-usage',
-      ],
-    },
-  ],
-  audits: [
-    'byte-efficiency/unused-javascript',
-  ],
-  // @ts-ignore TODO(bckenny): type extended Config where e.g. category.title isn't required
-  categories: {
-    'performance': {
-      auditRefs: [
-        {id: 'unused-javascript', weight: 0, group: 'load-opportunities'},
-      ],
-    },
-  },
 };
 
 module.exports = fullConfig;
diff --git a/lighthouse-core/gather/gatherers/js-usage.js b/lighthouse-core/gather/gatherers/js-usage.js
@@ -16,7 +16,7 @@ class JsUsage extends Gatherer {
    */
   async beforePass(passContext) {
     await passContext.driver.sendCommand('Profiler.enable');
-    await passContext.driver.sendCommand('Profiler.startPreciseCoverage');
+    await passContext.driver.sendCommand('Profiler.startPreciseCoverage', {detailed: false});
   }
 
   /**

diff --git a/lighthouse-core/lib/i18n/locales/en-US.json b/lighthouse-core/lib/i18n/locales/en-US.json
@@ -462,7 +462,7 @@
     "message": "Remove unused CSS"
   },
   "lighthouse-core/audits/byte-efficiency/unused-javascript.js | description": {
-    "message": "Remove unused JavaScript to reduce bytes consumed by network activity."
+    "message": "Remove unused JavaScript to reduce bytes consumed by network activity. [Learn more](https://developers.google.com/web/fundamentals/performance/optimizing-javascript/code-splitting)."
   },
   "lighthouse-core/audits/byte-efficiency/unused-javascript.js | title": {
     "message": "Remove unused JavaScript"

diff --git a/lighthouse-core/lib/i18n/locales/en-XL.json b/lighthouse-core/lib/i18n/locales/en-XL.json
@@ -462,7 +462,7 @@
     "message": "R̂ém̂óv̂é ûńûśêd́ ĈŚŜ"
   },
   "lighthouse-core/audits/byte-efficiency/unused-javascript.js | description": {
-    "message": "R̂ém̂óv̂é ûńûśêd́ Ĵáv̂áŜćr̂íp̂t́ t̂ó r̂éd̂úĉé b̂ýt̂éŝ ćôńŝúm̂éd̂ b́ŷ ńêt́ŵór̂ḱ âćt̂ív̂ít̂ý."
+    "message": "R̂ém̂óv̂é ûńûśêd́ Ĵáv̂áŜćr̂íp̂t́ t̂ó r̂éd̂úĉé b̂ýt̂éŝ ćôńŝúm̂éd̂ b́ŷ ńêt́ŵór̂ḱ âćt̂ív̂ít̂ý. [L̂éâŕn̂ ḿôŕê](https://developers.google.com/web/fundamentals/performance/optimizing-javascript/code-splitting)."
   },
   "lighthouse-core/audits/byte-efficiency/unused-javascript.js | title": {
     "message": "R̂ém̂óv̂é ûńûśêd́ Ĵáv̂áŜćr̂íp̂t́"

diff --git a/lighthouse-core/test/results/artifacts/artifacts.json b/lighthouse-core/test/results/artifacts/artifacts.json
@@ -346,6 +346,7 @@
       "requestId": "75994.22"
     }
   ],
+  "JsUsage": [],
   "CSSUsage": {
     "rules": [
       {

diff --git a/lighthouse-core/test/results/sample_v2.json b/lighthouse-core/test/results/sample_v2.json
@@ -2569,6 +2569,22 @@
         "overallSavingsBytes": 0
       }
     },
+    "unused-javascript": {
+      "id": "unused-javascript",
+      "title": "Remove unused JavaScript",
+      "description": "Remove unused JavaScript to reduce bytes consumed by network activity. [Learn more](https://developers.google.com/web/fundamentals/performance/optimizing-javascript/code-splitting).",
+      "score": 1,
+      "scoreDisplayMode": "numeric",
+      "numericValue": 0,
+      "displayValue": "",
+      "details": {
+        "type": "opportunity",
+        "headings": [],
+        "items": [],
+        "overallSavingsMs": 0,
+        "overallSavingsBytes": 0
+      }
+    },
     "uses-webp-images": {
       "id": "uses-webp-images",
       "title": "Serve images in next-gen formats",
@@ -3532,6 +3548,11 @@
           "weight": 0,
           "group": "load-opportunities"
         },
+        {
+          "id": "unused-javascript",
+          "weight": 0,
+          "group": "load-opportunities"
+        },
         {
           "id": "uses-optimized-images",
           "weight": 0,
@@ -5078,6 +5099,12 @@
         "duration": 100,
         "entryType": "measure"
       },
+      {
+        "startTime": 0,
+        "name": "lh:audit:unused-javascript",
+        "duration": 100,
+        "entryType": "measure"
+      },
       {
         "startTime": 0,
         "name": "lh:audit:uses-webp-images",
@@ -6158,6 +6185,12 @@
       "lighthouse-core/audits/byte-efficiency/unused-css-rules.js | description": [
         "audits[unused-css-rules].description"
       ],
+      "lighthouse-core/audits/byte-efficiency/unused-javascript.js | title": [
+        "audits[unused-javascript].title"
+      ],
+      "lighthouse-core/audits/byte-efficiency/unused-javascript.js | description": [
+        "audits[unused-javascript].description"
+      ],
       "lighthouse-core/audits/byte-efficiency/uses-webp-images.js | title": [
         "audits[uses-webp-images].title"
       ],

diff --git a/proto/sample_v2_round_trip.json b/proto/sample_v2_round_trip.json
@@ -2851,6 +2851,21 @@
             "scoreDisplayMode": "numeric",
             "title": "Remove unused CSS"
         },
+        "unused-javascript": {
+            "description": "Remove unused JavaScript to reduce bytes consumed by network activity. [Learn more](https://developers.google.com/web/fundamentals/performance/optimizing-javascript/code-splitting).",
+            "details": {
+                "headings": [],
+                "items": [],
+                "overallSavingsBytes": 0.0,
+                "overallSavingsMs": 0.0,
+                "type": "opportunity"
+            },
+            "id": "unused-javascript",
+            "numericValue": 0.0,
+            "score": 1.0,
+            "scoreDisplayMode": "numeric",
+            "title": "Remove unused JavaScript"
+        },
         "use-landmarks": {
             "description": "Landmark elements (<main>, <nav>, etc.) are used to improve the keyboard navigation of the page for assistive technology. [Learn more](https://web.dev/use-landmarks/).",
             "id": "use-landmarks",
@@ -3696,6 +3711,11 @@
                     "id": "unused-css-rules",
                     "weight": 0.0
                 },
+                {
+                    "group": "load-opportunities",
+                    "id": "unused-javascript",
+                    "weight": 0.0
+                },
                 {
                     "group": "load-opportunities",
                     "id": "uses-optimized-images",
@@ -4979,6 +4999,12 @@
                 "name": "lh:audit:unused-css-rules",
                 "startTime": 0.0
             },
+            {
+                "duration": 100.0,
+                "entryType": "measure",
+                "name": "lh:audit:unused-javascript",
+                "startTime": 0.0
+            },
             {
                 "duration": 100.0,
                 "entryType": "measure",