new_audit: add charset declaration audit

lighthouse-core/audits/dobetterweb/charset.js

@@ -0,0 +1,84 @@
+/**
+ * @license Copyright 2016 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.
+ */
+
+/**
+ * @fileoverview Audits a page to ensure charset it configured properly.
+ * It must be defined within the first 1024 bytes of the HTML document, defined in the HTTP header, or in a BOM.
+ */
+'use strict';
+
+const Audit = require('../audit.js');
+const i18n = require('../../lib/i18n/i18n.js');
+const MainResource = require('../../computed/main-resource.js');
+const CONTENT_TYPE_HEADER = 'content-type';
+const CHARSET_META_REGEX = /<meta.*charset="?.{1,}"?.*>/gm;
+const CHARSET_HTTP_REGEX = /charset=.{1,}/gm;
+
+const UIStrings = {
+  /** Title of a Lighthouse audit that provides detail on if the charset is set properly for a page. This title is shown when the charset is defined correctly. */
+  title: 'Properly defines charset',
+  /** Title of a Lighthouse audit that provides detail on if the charset is set properly for a page. This title is shown when the charset meta tag is missing or defined too late in the page. */
+  failureTitle: 'Charset element is missing or occurs too late on the page',
+  /** Description of a Lighthouse audit that tells the user why the charset needs to be defined early on. */
+  description: 'A character encoding declaration is required whether it is done explicitly ' +
+    'in the first 1024 bytes of the page source, through a Byte Order Mark (BOM), ' +
+    'or in the content-type HTTP header. ' +
+    '[Learn more](https://www.w3.org/International/questions/qa-html-encoding-declarations).',
+};
+
+const str_ = i18n.createMessageInstanceIdFn(__filename, UIStrings);
+
+class CharsetDefined extends Audit {
+  /**
+   * @return {LH.Audit.Meta}
+   */
+  static get meta() {
+    return {
+      id: 'charset',
+      title: str_(UIStrings.title),
+      failureTitle: str_(UIStrings.failureTitle),
+      description: str_(UIStrings.description),
+      requiredArtifacts: ['MainDocumentContent', 'URL', 'devtoolsLogs'],
+    };
+  }
+
+  /**
+   * @param {LH.Artifacts} artifacts
+   * @param {LH.Audit.Context} context
+   * @return {Promise<LH.Audit.Product>}
+   */
+  static audit(artifacts, context) {
+    const devtoolsLog = artifacts.devtoolsLogs[Audit.DEFAULT_PASS];
+    return MainResource.request({devtoolsLog, URL: artifacts.URL}, context)
+    .then(mainResource => {
+      let charsetIsSet = false;
+      // Check the http header 'content-type' to see if charset is defined there
+      if (mainResource.responseHeaders) {
+        const contentTypeHeader = mainResource.responseHeaders
+          .find(header => header.name.toLowerCase() === CONTENT_TYPE_HEADER);
+
+        if (contentTypeHeader) {
+          charsetIsSet = contentTypeHeader.value.match(CHARSET_HTTP_REGEX) !== null;
+        }
+      }
+
+      // Check if there is a BOM byte marker
+      const BOM_FIRSTCHAR = 65279;
+      charsetIsSet = charsetIsSet || artifacts.MainDocumentContent.charCodeAt(0) === BOM_FIRSTCHAR;
+
+      // Check if charset is defined within the first 1024 characters(~1024 bytes) of the HTML document
+      charsetIsSet = charsetIsSet ||
+        artifacts.MainDocumentContent.slice(0, 1024).match(CHARSET_META_REGEX) !== null;
+
+      return {
+        score: Number(charsetIsSet),
+      };
+    });
+  }
+}
+
+module.exports = CharsetDefined;
+module.exports.UIStrings = UIStrings;

lighthouse-core/config/default-config.js

@@ -287,6 +287,7 @@ const defaultConfig = {
     'byte-efficiency/efficient-animated-content',
     'dobetterweb/appcache-manifest',
     'dobetterweb/doctype',
+    'dobetterweb/charset',
     'dobetterweb/dom-size',
     'dobetterweb/external-anchors-use-rel-noopener',
     'dobetterweb/geolocation-on-start',
@@ -505,6 +506,7 @@ const defaultConfig = {
         {id: 'external-anchors-use-rel-noopener', weight: 1},
         {id: 'geolocation-on-start', weight: 1},
         {id: 'doctype', weight: 1},
+        {id: 'charset', weight: 1},
         {id: 'no-vulnerable-libraries', weight: 1},
         {id: 'js-libraries', weight: 0},
         {id: 'notification-on-start', weight: 1},

lighthouse-core/lib/i18n/i18n.js

@@ -297,7 +297,7 @@ function _formatIcuMessage(locale, icuMessageId, uiStringMessage, values = {}) {
   }
   // At this point, there is no reasonable string to show to the user, so throw.
   if (!localeMessage) {
-    throw new Error(_ICUMsgNotFoundMsg);
+    throw new Error(_ICUMsgNotFoundMsg + icuMessageId + uiStringMessage);
   }
 
   // when using accented english, force the use of a different locale for number formatting

lighthouse-core/lib/i18n/locales/en-US.json

@@ -554,6 +554,15 @@
   "lighthouse-core/audits/dobetterweb/appcache-manifest.js | title": {
     "message": "Avoids Application Cache"
   },
+  "lighthouse-core/audits/dobetterweb/charset.js | description": {
+    "message": "A character encoding declaration is required whether it is done explicitly in the first 1024 bytes of the page source, through a Byte Order Mark (BOM), or in the content-type HTTP header. [Learn more](https://www.w3.org/International/questions/qa-html-encoding-declarations)."
+  },
+  "lighthouse-core/audits/dobetterweb/charset.js | failureTitle": {
+    "message": "Charset element is missing or occurs too late on the page"
+  },
+  "lighthouse-core/audits/dobetterweb/charset.js | title": {
+    "message": "Properly defines charset"
+  },
   "lighthouse-core/audits/dobetterweb/doctype.js | description": {
     "message": "Specifying a doctype prevents the browser from switching to quirks-mode. [Learn more](https://web.dev/doctype)."
   },

lighthouse-core/lib/i18n/locales/en-XL.json

@@ -554,6 +554,15 @@
   "lighthouse-core/audits/dobetterweb/appcache-manifest.js | title": {
     "message": "Âv́ôíd̂ś Âṕp̂ĺîćât́îón̂ Ćâćĥé"
   },
+  "lighthouse-core/audits/dobetterweb/charset.js | description": {
+    "message": "Â ćĥár̂áĉt́êŕ êńĉód̂ín̂ǵ d̂éĉĺâŕât́îón̂ íŝ ŕêq́ûír̂éd̂ ẃĥét̂h́êŕ ît́ îś d̂ón̂é êx́p̂ĺîćît́l̂ý îń t̂h́ê f́îŕŝt́ 1024 b̂ýt̂éŝ óf̂ t́ĥé p̂áĝé ŝóûŕĉé, t̂h́r̂óûǵĥ á B̂ýt̂é Ôŕd̂ér̂ Ḿâŕk̂ (B́ÔḾ), ôŕ îń t̂h́ê ćôńt̂én̂t́-t̂ýp̂é ĤT́T̂Ṕ ĥéâd́êŕ. [L̂éâŕn̂ ḿôŕê](https://www.w3.org/International/questions/qa-html-encoding-declarations)."
+  },
+  "lighthouse-core/audits/dobetterweb/charset.js | failureTitle": {
+    "message": "Ĉh́âŕŝét̂ él̂ém̂én̂t́ îś m̂íŝśîńĝ ór̂ óĉćûŕŝ t́ôó l̂át̂é ôń t̂h́ê ṕâǵê"
+  },
+  "lighthouse-core/audits/dobetterweb/charset.js | title": {
+    "message": "P̂ŕôṕêŕl̂ý d̂éf̂ín̂éŝ ćĥár̂śêt́"
+  },
   "lighthouse-core/audits/dobetterweb/doctype.js | description": {
     "message": "Ŝṕêćîf́ŷín̂ǵ â d́ôćt̂ýp̂é p̂ŕêv́êńt̂ś t̂h́ê b́r̂óŵśêŕ f̂ŕôḿ ŝẃît́ĉh́îńĝ t́ô q́ûír̂ḱŝ-ḿôd́ê. [Ĺêár̂ń m̂ór̂é](https://web.dev/doctype)."
   },

lighthouse-core/test/audits/dobetterweb/charset-test.js

@@ -0,0 +1,185 @@
+/**
+ * @license Copyright 2016 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 CharsetDefinedAudit = require('../../../audits/dobetterweb/charset.js');
+const assert = require('assert');
+const networkRecordsToDevtoolsLog = require('../../network-records-to-devtools-log.js');
+
+/* eslint-env jest */
+
+describe('Charset defined audit', () => {
+  it('succeeds when the page contains the charset meta tag', () => {
+    const finalUrl = 'https://example.com/';
+    const mainResource = {
+      url: finalUrl,
+      responseHeaders: [],
+    };
+    const devtoolsLog = networkRecordsToDevtoolsLog([mainResource]);
+    const artifacts = {
+      devtoolsLogs: {[CharsetDefinedAudit.DEFAULT_PASS]: devtoolsLog},
+      URL: {finalUrl},
+      MainDocumentContent: '<meta charset="utf-8" />',
+    };
+
+    const context = {computedCache: new Map()};
+    return CharsetDefinedAudit.audit(artifacts, context).then(auditResult => {
+      assert.equal(auditResult.score, 1);
+    });
+  });
+
+  it('succeeds when the page has the charset defined in the content-type meta tag', () => {
+    const finalUrl = 'https://example.com/';
+    const mainResource = {
+      url: finalUrl,
+      responseHeaders: [],
+    };
+    const devtoolsLog = networkRecordsToDevtoolsLog([mainResource]);
+    const artifacts = {
+      devtoolsLogs: {[CharsetDefinedAudit.DEFAULT_PASS]: devtoolsLog},
+      URL: {finalUrl},
+      MainDocumentContent: '<meta http-equiv="Content-type" content="text/html; charset=utf-8" />',
+    };
+
+    const context = {computedCache: new Map()};
+    return CharsetDefinedAudit.audit(artifacts, context).then(auditResult => {
+      assert.equal(auditResult.score, 1);
+    });
+  });
+
+  it('succeeds when the page has the charset defined in the content-type http header', () => {
+    const finalUrl = 'https://example.com/';
+    const mainResource = {
+      url: finalUrl,
+      responseHeaders: [
+        {name: 'content-type', value: 'text/html; charset=UTF-8'},
+      ],
+    };
+    const devtoolsLog = networkRecordsToDevtoolsLog([mainResource]);
+    const artifacts = {
+      devtoolsLogs: {[CharsetDefinedAudit.DEFAULT_PASS]: devtoolsLog},
+      URL: {finalUrl},
+      MainDocumentContent: '<meta http-equiv="Content-type" content="text/html" />',
+    };
+
+    const context = {computedCache: new Map()};
+    return CharsetDefinedAudit.audit(artifacts, context).then(auditResult => {
+      assert.equal(auditResult.score, 1);
+    });
+  });
+
+  it('succeeds when the page has the charset defined via BOM', () => {
+    const finalUrl = 'https://example.com/';
+    const mainResource = {
+      url: finalUrl,
+      responseHeaders: [
+        {name: 'content-type', value: 'text/html'},
+      ],
+    };
+    const devtoolsLog = networkRecordsToDevtoolsLog([mainResource]);
+    const artifacts = {
+      devtoolsLogs: {[CharsetDefinedAudit.DEFAULT_PASS]: devtoolsLog},
+      URL: {finalUrl},
+      MainDocumentContent: '\ufeff<meta http-equiv="Content-type" content="text/html" />',
+    };
+
+    const context = {computedCache: new Map()};
+    return CharsetDefinedAudit.audit(artifacts, context).then(auditResult => {
+      assert.equal(auditResult.score, 1);
+    });
+  });
+
+  it('fails when the page does not have charset defined', () => {
+    const finalUrl = 'https://example.com/';
+    const mainResource = {
+      url: finalUrl,
+      responseHeaders: [
+        {name: 'content-type', value: 'text/html'},
+      ],
+    };
+    const devtoolsLog = networkRecordsToDevtoolsLog([mainResource]);
+    const artifacts = {
+      devtoolsLogs: {[CharsetDefinedAudit.DEFAULT_PASS]: devtoolsLog},
+      URL: {finalUrl},
+      MainDocumentContent: '<meta http-equiv="Content-type" content="text/html" />',
+    };
+
+    const context = {computedCache: new Map()};
+    return CharsetDefinedAudit.audit(artifacts, context).then(auditResult => {
+      assert.equal(auditResult.score, 0);
+    });
+  });
+
+  it('fails when the page has charset defined too late in the page', () => {
+    const finalUrl = 'https://example.com/';
+    const mainResource = {
+      url: finalUrl,
+      responseHeaders: [
+        {name: 'content-type', value: 'text/html'},
+      ],
+    };
+    const bigString = new Array(1024).fill(' ').join('');
+    const devtoolsLog = networkRecordsToDevtoolsLog([mainResource]);
+    const artifacts = {
+      devtoolsLogs: {[CharsetDefinedAudit.DEFAULT_PASS]: devtoolsLog},
+      URL: {finalUrl},
+      MainDocumentContent: '<html><head>' + bigString + '<meta charset="utf-8" />hello',
+    };
+
+    const context = {computedCache: new Map()};
+    return CharsetDefinedAudit.audit(artifacts, context).then(auditResult => {
+      assert.equal(auditResult.score, 0);
+    });
+  });
+
+  it('passes when the page has charset defined almost too late in the page', () => {
+    const finalUrl = 'https://example.com/';
+    const mainResource = {
+      url: finalUrl,
+      responseHeaders: [
+        {name: 'content-type', value: 'text/html'},
+      ],
+    };
+    const bigString = new Array(900).fill(' ').join('');
+    const devtoolsLog = networkRecordsToDevtoolsLog([mainResource]);
+    const artifacts = {
+      devtoolsLogs: {[CharsetDefinedAudit.DEFAULT_PASS]: devtoolsLog},
+      URL: {finalUrl},
+      MainDocumentContent: '<html><head>' + bigString + '<meta charset="utf-8" />hello',
+    };
+
+    const context = {computedCache: new Map()};
+    return CharsetDefinedAudit.audit(artifacts, context).then(auditResult => {
+      assert.equal(auditResult.score, 1);
+    });
+  });
+
+  it('fails when charset only partially defined in the first 1024 bytes of the page', () => {
+    const finalUrl = 'https://example.com/';
+    const mainResource = {
+      url: finalUrl,
+      responseHeaders: [
+        {name: 'content-type', value: 'text/html'},
+      ],
+    };
+    const prelude = '<html><head>';
+    const charsetHTML = '<meta charset="utf-8" />';
+    // 1024 bytes should be halfway through the meta tag
+    const bigString = new Array(1024 - prelude.length - charsetHTML.length / 2).fill(' ').join('');
+
+    const devtoolsLog = networkRecordsToDevtoolsLog([mainResource]);
+    const artifacts = {
+      devtoolsLogs: {[CharsetDefinedAudit.DEFAULT_PASS]: devtoolsLog},
+      URL: {finalUrl},
+      MainDocumentContent: prelude + bigString + charsetHTML + 'hello',
+    };
+
+    const context = {computedCache: new Map()};
+    return CharsetDefinedAudit.audit(artifacts, context).then(auditResult => {
+      assert.equal(auditResult.score, 0);
+    });
+  });
+});

lighthouse-core/test/results/sample_v2.json

@@ -2782,6 +2782,13 @@
       "score": 1,
       "scoreDisplayMode": "binary"
     },
+    "charset": {
+      "id": "charset",
+      "title": "Properly defines charset",
+      "description": "A character encoding declaration is required whether it is done explicitly in the first 1024 bytes of the page source, through a Byte Order Mark (BOM), or in the content-type HTTP header. [Learn more](https://www.w3.org/International/questions/qa-html-encoding-declarations).",
+      "score": 1,
+      "scoreDisplayMode": "binary"
+    },
     "dom-size": {
       "id": "dom-size",
       "title": "Avoids an excessive DOM size",
@@ -4042,6 +4049,10 @@
           "id": "doctype",
           "weight": 1
         },
+        {
+          "id": "charset",
+          "weight": 1
+        },
         {
           "id": "no-vulnerable-libraries",
           "weight": 1
@@ -4072,7 +4083,7 @@
         }
       ],
       "id": "best-practices",
-      "score": 0.07
+      "score": 0.13
     },
     "seo": {
       "title": "SEO",
@@ -5223,6 +5234,12 @@
         "duration": 100,
         "entryType": "measure"
       },
+      {
+        "startTime": 0,
+        "name": "lh:audit:charset",
+        "duration": 100,
+        "entryType": "measure"
+      },
       {
         "startTime": 0,
         "name": "lh:audit:dom-size",
@@ -6349,6 +6366,12 @@
       "lighthouse-core/audits/dobetterweb/doctype.js | description": [
         "audits.doctype.description"
       ],
+      "lighthouse-core/audits/dobetterweb/charset.js | title": [
+        "audits.charset.title"
+      ],
+      "lighthouse-core/audits/dobetterweb/charset.js | description": [
+        "audits.charset.description"
+      ],
       "lighthouse-core/audits/dobetterweb/dom-size.js | title": [
         "audits[dom-size].title"
       ],