GoogleChrome · paulirish · Oct 19, 2017 · Oct 5, 2017 · Oct 5, 2017 · Oct 5, 2017
diff --git a/lighthouse-cli/test/fixtures/seo/seo-failure-cases.html b/lighthouse-cli/test/fixtures/seo/seo-failure-cases.html
@@ -13,6 +13,11 @@
   <!-- no <meta name="description" content=""> -->
 </head>
 <body>
-  bad crawlz
+  <h1>SEO</h1>
+
+  <h2>Anchor text</h2>
+  <a href='https://example.com'>click this</a>
+  <a href='/test.html'> click this </a>
+  <a href='/test.html'>CLICK THIS</a>
 </body>
 </html>
diff --git a/lighthouse-cli/test/fixtures/seo/seo-tester.html b/lighthouse-cli/test/fixtures/seo/seo-tester.html
@@ -13,6 +13,12 @@
   <meta name="description" content="The premiere destination for testing your SEO audit gathering">
 </head>
 <body>
-  crawlz me
+  <h1>SEO</h1>
+
+  <h2>Anchor text</h2>
+  <a href='https://example.com'>descriptive link</a>
+  <a href='#non-descriptive-local'>click this</a>
+  <a href='https://example.com/non-descriptive-no-follow.html' rel="nofollow">click this</a>
+  <a href='javascript:void(0);'>click this</a>
 </body>
 </html>
diff --git a/lighthouse-cli/test/smokehouse/seo/expectations.js b/lighthouse-cli/test/smokehouse/seo/expectations.js
@@ -25,6 +25,9 @@ module.exports = [
       'http-status-code': {
         score: true,
       },
+      'anchor-text': {
+        score: true,
+      },
     },
   },
   {
@@ -49,6 +52,15 @@ module.exports = [
         score: false,
         displayValue: '403',
       },
+      'anchor-text': {
+        score: false,
+        displayValue: '3 anchors found',
+        details: {
+          items: {
+            length: 3,
+          },
+        },
+      },
     },
   },
 ];
diff --git a/lighthouse-core/audits/seo/anchor-text.js b/lighthouse-core/audits/seo/anchor-text.js
@@ -0,0 +1,76 @@
+/**
+ * @license Copyright 2017 Google Inc. 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');
+const URL = require('../../lib/url-shim');
+const BLOCKLIST = new Set([
+  'click here',
+  'click this',
+  'go',
+  'here',
+  'this',
+  'start',
+  'right here',
+  'more',
+  'learn more',
+]);
+
+class AnchorText extends Audit {
+  /**
+   * @return {!AuditMeta}
+   */
+  static get meta() {
+    return {
+      category: 'Content Best Practices',
+      name: 'anchor-text',
+      description: 'Anchors have descriptive text.',
+      failureDescription: 'Anchors do not have descriptive text',
+      helpText: 'Descriptive anchor text helps search engines understand your content. ' +
+      '[Learn more](https://webmasters.googleblog.com/2008/10/importance-of-link-architecture.html)',
+      requiredArtifacts: ['URL', 'CrawlableAnchors'],
+    };
+  }
+
+  /**
+   * @param {!Artifacts} artifacts
+   * @return {!AuditResult}
+   */
+  static audit(artifacts) {
+    const failingAnchors = artifacts.CrawlableAnchors
+      .filter(anchor => {
+        if (
+          anchor.href.toLowerCase().startsWith('javascript:') ||
+          URL.equalWithExcludedFragments(anchor.href, artifacts.URL.finalUrl)
+        ) {
+          return false;
+        }
+
+        return BLOCKLIST.has(anchor.text.trim().toLowerCase());
+      });
+
+    const headings = [
+      {key: 'href', itemType: 'url', text: 'Link destination'},
+      {key: 'text', itemType: 'text', text: 'Link Text'},
+    ];
+
+    const details = Audit.makeTableDetails(headings, failingAnchors);
+    let displayValue;
+
+    if (failingAnchors.length) {
+      displayValue = failingAnchors.length > 1 ?
+        `${failingAnchors.length} anchors found` : '1 anchor found';
+    }
+
+    return {
+      rawValue: failingAnchors.length === 0,
+      details,
+      displayValue,
+    };
+  }
+}
+
+module.exports = AnchorText;
diff --git a/lighthouse-core/config/seo.js b/lighthouse-core/config/seo.js
@@ -11,11 +11,13 @@ module.exports = {
     passName: 'defaultPass',
     gatherers: [
       'seo/meta-description',
+      'seo/crawlable-anchors',
     ],
   }],
   audits: [
     'seo/meta-description',
     'seo/http-status-code',
+    'seo/anchor-text',
   ],
   groups: {
     'seo-mobile': {
@@ -41,6 +43,7 @@ module.exports = {
         {id: 'document-title', weight: 1, group: 'seo-content'},
         {id: 'meta-description', weight: 1, group: 'seo-content'},
         {id: 'http-status-code', weight: 1, group: 'seo-crawl'},
+        {id: 'anchor-text', weight: 1, group: 'seo-content'},
       ],
     },
   },

diff --git a/lighthouse-core/gather/gatherers/seo/crawlable-anchors.js b/lighthouse-core/gather/gatherers/seo/crawlable-anchors.js
@@ -0,0 +1,33 @@
+/**
+ * @license Copyright 2017 Google Inc. 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 Gatherer = require('../gatherer');
+const DOMHelpers = require('../../../lib/dom-helpers.js');
+
+class CrawlableAnchors extends Gatherer {
+  /**
+   * @param {{driver: !Object}} options Run options
+   * @return {!Promise<!Array<{href: string, text: string}>>}
+   */
+  afterPass(options) {
+    const expression = `(function() {
+      ${DOMHelpers.getElementsInDocumentFnString}; // define function on page
+      const selector = 'a[href]:not([rel~="nofollow"])';
+      const elements = getElementsInDocument(selector);
+      return elements
+        .map(node => ({
+          href: node.href,
+          text: node.innerText
+        }));
+    })()`;
+
+    return options.driver.evaluateAsync(expression);
+  }
+}
+
+module.exports = CrawlableAnchors;
+
diff --git a/lighthouse-core/test/audits/seo/anchor-text-test.js b/lighthouse-core/test/audits/seo/anchor-text-test.js
@@ -0,0 +1,82 @@
+/**
+ * @license Copyright 2017 Google Inc. 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 AnchorTextAudit = require('../../../audits/seo/anchor-text.js');
+const assert = require('assert');
+
+/* eslint-env mocha */
+
+describe('SEO: anchor text audit', () => {
+  it('fails when anchor with non descriptive text is found', () => {
+    const invalidAnchor = {href: 'https://example.com/otherpage.html', text: 'click here'};
+    const artifacts = {
+      URL: {
+        finalUrl: 'https://example.com/page.html',
+      },
+      CrawlableAnchors: [
+        {href: 'https://example.com/otherpage.html', text: 'legit anchor text'},
+        invalidAnchor,
+        {href: 'https://example.com/otherpage.html', text: 'legit anchor text'},
+      ],
+    };
+
+    const auditResult = AnchorTextAudit.audit(artifacts);
+    assert.equal(auditResult.rawValue, false);
+    assert.equal(auditResult.details.items.length, 1);
+    assert.equal(auditResult.details.items[0][0].text, invalidAnchor.href);
+    assert.equal(auditResult.details.items[0][1].text, invalidAnchor.text);
+  });
+
+  it('ignores links pointing to the main document', () => {
+    const artifacts = {
+      URL: {
+        finalUrl: 'https://example.com/page.html',
+      },
+      CrawlableAnchors: [
+        {href: 'https://example.com/otherpage.html', text: 'legit anchor text'},
+        {href: 'https://example.com/page.html', text: 'click here'},
+        {href: 'https://example.com/page.html#test', text: 'click here'},
+        {href: 'https://example.com/otherpage.html', text: 'legit anchor text'},
+      ],
+    };
+
+    const auditResult = AnchorTextAudit.audit(artifacts);
+    assert.equal(auditResult.rawValue, true);
+  });
+
+  it('ignores javascript: links', () => {
+    const artifacts = {
+      URL: {
+        finalUrl: 'https://example.com/page.html',
+      },
+      CrawlableAnchors: [
+        {href: 'javascript:alert(1)', text: 'click here'},
+        {href: 'JavaScript:window.location="/otherpage.html"', text: 'click here'},
+        {href: 'JAVASCRIPT:void(0)', text: 'click here'},
+      ],
+    };
+
+    const auditResult = AnchorTextAudit.audit(artifacts);
+    assert.equal(auditResult.rawValue, true);
+  });
+
+  it('passes when all anchors have descriptive texts', () => {
+    const artifacts = {
+      URL: {
+        finalUrl: 'https://example.com/page.html',
+      },
+      CrawlableAnchors: [
+        {href: 'https://example.com/otherpage.html', text: 'legit anchor text'},
+        {href: 'http://example.com/page.html?test=test', text: 'legit anchor text'},
+        {href: 'file://Users/user/Desktop/file.png', text: 'legit anchor text'},
+      ],
+    };
+
+    const auditResult = AnchorTextAudit.audit(artifacts);
+    assert.equal(auditResult.rawValue, true);
+  });
+});