Use v8 Stack Trace API

lighthouse-core/audits/dobetterweb/no-datenow.js

@@ -55,15 +55,19 @@ class NoDateNowAudit extends Audit {
     }
 
     const pageHost = url.parse(artifacts.URL.finalUrl).host;
-
-    // Filter out Date.now() usage from scripts on other domains.
-    const results = artifacts.DateNowUse.errors.reduce((prev, err) => {
-      if (url.parse(err.url).host === pageHost) {
-        err.url = `${JSON.stringify(err)}`;
-        prev.push(err);
+    // Filter out Date.now() usage if script was on another host or an error with
+    // the same url:line:col combo has already been seen.
+    const results = artifacts.DateNowUse.dateNowUses.reduce((prev, err) => {
+      const jsonStr = JSON.stringify(err);
+      if (url.parse(err.url).host === pageHost && prev.indexOf(jsonStr) === -1) {
+        prev.push(jsonStr);
       }
       return prev;
-    }, []);
+    }, []).map(err => {
+      err = JSON.parse(err);
+      err.misc = `(line: ${err.line}, col: ${err.col})`;
+      return err;
+    });
 
     return NoDateNowAudit.generateAuditResult({
       rawValue: results.length === 0,

lighthouse-core/formatters/partials/url-list.html

@@ -5,7 +5,8 @@
   .http-resource__url {
     margin-right: 8px;
   }
-  .http-resource__protocol {
+  .http-resource__protocol,
+  .http-resource__misc {
     color: #999;
   }
 </style>
@@ -19,6 +20,9 @@
         {{#if this.protocol}}
           <span class="http-resource__protocol">({{this.protocol}})</span>
         {{/if}}
+        {{#if this.misc}}
+          <span class="http-resource__misc">{{this.misc}}</span>
+        {{/if}}
       </div>
     {{/each}}
   </details>

lighthouse-core/gather/gatherers/dobetterweb/datenow.js

@@ -28,21 +28,22 @@ const Gatherer = require('../gatherer');
 function patchDateNow() {
   window.__stackTraceErrors = [];
   // Override Date.now() so we know when if it's called.
-  const orig = Date.now;
+  const origDateNow = Date.now;
+  const originalPrepareStackTrace = Error.prepareStackTrace;
   Date.now = function() {
-    try {
-      throw Error('__called Date.now()__');
-    } catch (e) {
-      if (e.stack) {
-        const split = e.stack.split('\n');
-        const m = split[split.length - 1].match(/(https?:\/\/.*):(\d+):(\d+)/);
-        if (m) {
-          window.__stackTraceErrors.push({url: m[1], line: m[2], col: m[3]});
-        }
-      }
-    }
-
-    return orig();
+    // See v8's Stack Trace API https://github.com/v8/v8/wiki/Stack-Trace-API#customizing-stack-traces
+    Error.prepareStackTrace = function(error, structStackTrace) {
+      const lastCallFrame = structStackTrace[structStackTrace.length - 1];
+      const file = lastCallFrame.getFileName();
+      const line = lastCallFrame.getLineNumber();
+      const col = lastCallFrame.getColumnNumber();
+      window.__stackTraceErrors.push({url: file, line, col});
+      return {url: file, line, col}; // return value populates e.stack.
+    };
+    Error.captureStackTrace(new Error('__called Date.now()__'));
+    // Remove custom formatter so future results use v8's formatter.
+    Error.prepareStackTrace = originalPrepareStackTrace;
+    return origDateNow();
   };
 }
 
@@ -58,8 +59,8 @@ class DateNowUse extends Gatherer {
 
   afterPass(options) {
     return options.driver.evaluateAsync(`(${collectDateNowUsage.toString()}())`)
-        .then(errors => {
-          this.artifact.errors = errors;
+        .then(dateNowUses => {
+          this.artifact.dateNowUses = dateNowUses;
         }, _ => {
           this.artifact = -1;
           return;

lighthouse-core/test/audits/dobetterweb/no-datenow-test.js

@@ -31,7 +31,21 @@ describe('Page does not use Date.now()', () => {
 
   it('passes when Date.now() is not used', () => {
     const auditResult = DateNowUseAudit.audit({
-      DateNowUse: {errors: []},
+      DateNowUse: {dateNowUses: []},
+      URL: {finalUrl: URL},
+    });
+    assert.equal(auditResult.rawValue, true);
+    assert.equal(auditResult.extendedInfo.value.length, 0);
+  });
+
+  it('passes when Date.now() is used on a different origin', () => {
+    const auditResult = DateNowUseAudit.audit({
+      DateNowUse: {
+        dateNowUses: [
+          {url: 'http://different.com/two', line: 2, col: 2},
+          {url: 'http://example2.com/two', line: 2, col: 22}
+        ]
+      },
       URL: {finalUrl: URL},
     });
     assert.equal(auditResult.rawValue, true);
@@ -41,10 +55,10 @@ describe('Page does not use Date.now()', () => {
   it('fails when Date.now() is used on the origin', () => {
     const auditResult = DateNowUseAudit.audit({
       DateNowUse: {
-        errors: [
-          {url: 'http://example.com/one', line: '1', col: '1'},
-          {url: 'http://example.com/two', line: '10', col: '1'},
-          {url: 'http://example2.com/two', line: '2', col: '2'}
+        dateNowUses: [
+          {url: 'http://example.com/one', line: 1, col: 1},
+          {url: 'http://example.com/two', line: 10, col: 1},
+          {url: 'http://example2.com/two', line: 2, col: 22}
         ]
       },
       URL: {finalUrl: URL},
@@ -53,16 +67,17 @@ describe('Page does not use Date.now()', () => {
     assert.equal(auditResult.extendedInfo.value.length, 2);
   });
 
-  it('passes when Date.now() is only used on a different origin', () => {
+  it('same file:line:col usage is deduped', () => {
     const auditResult = DateNowUseAudit.audit({
       DateNowUse: {
-        errors: [
-          {url: 'http://different.com/two', line: '2', col: '2'}
+        dateNowUses: [
+          {url: 'http://example.com/dupe', line: 1, col: 1},
+          {url: 'http://example.com/dupe', line: 1, col: 1}
         ]
       },
       URL: {finalUrl: URL},
     });
-    assert.equal(auditResult.rawValue, true);
-    assert.equal(auditResult.extendedInfo.value.length, 0);
+    assert.equal(auditResult.rawValue, false);
+    assert.equal(auditResult.extendedInfo.value.length, 1);
   });
 });