Audit: DOM stats (total nodes, depth, width) #1673
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| <!doctype html> | ||
| <!-- | ||
| * 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. | ||
| --> | ||
| <html> | ||
| <head> | ||
| <title>DoBetterWeb - DOM size tester</title> | ||
| <meta charset="utf-8"> | ||
| <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0"> | ||
| </head> | ||
| <body> | ||
| <main> | ||
| <section> | ||
| <div> | ||
| <div>6</div> | ||
| </div> | ||
| <div> | ||
| <div> | ||
| <div id="attachshadow">7</div> | ||
| </div> | ||
| </div> | ||
| <div> | ||
| <template> | ||
| <div><div><div><div>10, but noop in template</div></div></div></div> | ||
| </template> | ||
| </div> | ||
| </section> | ||
| </main> | ||
| <footer> | ||
| <div id="attachshadow-big" class="test this out">4</div> | ||
| <div>3</div> | ||
| <div></div> | ||
| <div></div> | ||
| <div></div> | ||
| <div></div> | ||
| </footer> | ||
| <script> | ||
| function withShadowDOMTest() { | ||
| const el = document.querySelector('#attachshadow'); | ||
| el.innerHTML = `<div>7</div>`; | ||
| el.attachShadow({mode: 'open'}).innerHTML = ` | ||
| <div> | ||
| <div class="here">9</div> | ||
| </div> | ||
| `; | ||
|
|
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| const el2 = document.querySelector('#attachshadow-big'); | ||
| el2.attachShadow({mode: 'open'}).innerHTML = ` | ||
| <div> | ||
| <div>6</div> | ||
| <div>6</div> | ||
| <div>6</div> | ||
| <div>6</div> | ||
| <div>6</div> | ||
| <div>6</div> | ||
| <div>6</div> | ||
| <div>6</div> | ||
| <div>6</div> | ||
| </div> | ||
| `; | ||
| } | ||
|
|
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| function domTest(numNodes=1500) { | ||
| const frag = new DocumentFragment(); | ||
| for (let i = 0; i < numNodes; ++i) { | ||
| frag.appendChild(document.createElement('span')); | ||
| } | ||
| document.body.appendChild(frag); | ||
| } | ||
|
|
||
| const params = new URLSearchParams(location.search); | ||
| if (params.has('smallDOM')) { | ||
| domTest(1300); | ||
| } else if (params.has('largeDOM')) { | ||
| domTest(6000); | ||
| } | ||
| if (params.has('withShadowDOM')) { | ||
| withShadowDOMTest(); | ||
| } | ||
| </script> | ||
| </body> | ||
| </html> |
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| /** | ||
| * @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. | ||
| */ | ||
|
|
||
| /** | ||
| * @fileoverview Audits a page to see how the size of DOM it creates. Stats like | ||
| * tree depth, # children, and total nodes are returned. The score is calculated | ||
| * based solely on the total number of nodes found on the page. | ||
| */ | ||
|
|
||
| 'use strict'; | ||
|
|
||
| const Audit = require('../audit'); | ||
| const TracingProcessor = require('../../lib/traces/tracing-processor'); | ||
| const Formatter = require('../../formatters/formatter'); | ||
|
|
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| const MAX_DOM_NODES = 1500; | ||
| const MAX_DOM_TREE_WIDTH = 60; | ||
| const MAX_DOM_TREE_DEPTH = 32; | ||
|
|
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| // Parameters for log-normal CDF scoring. See https://www.desmos.com/calculator/9cyxpm5qgp. | ||
| const SCORING_POINT_OF_DIMINISHING_RETURNS = 2400; | ||
| const SCORING_MEDIAN = 3000; | ||
|
|
||
| class DOMSize extends Audit { | ||
| static get MAX_DOM_NODES() { | ||
| return MAX_DOM_NODES; | ||
| } | ||
|
|
||
| /** | ||
| * @return {!AuditMeta} | ||
| */ | ||
| static get meta() { | ||
| return { | ||
| category: 'Performance', | ||
| name: 'dom-size', | ||
| description: 'Avoids an excessive DOM size', | ||
| optimalValue: DOMSize.MAX_DOM_NODES.toLocaleString() + ' nodes', | ||
| helpText: 'Browser engineers recommend pages contain fewer than ' + | ||
| `~${DOMSize.MAX_DOM_NODES.toLocaleString()} DOM nodes. The sweet spot is a tree depth < ` + | ||
| `${MAX_DOM_TREE_DEPTH} elements and fewer than ${MAX_DOM_TREE_WIDTH} ` + | ||
| 'children/parent element. A large DOM can increase memory, cause longer ' + | ||
| '[style calculations](https://developers.google.com/web/fundamentals/performance/rendering/reduce-the-scope-and-complexity-of-style-calculations), ' + | ||
| 'and produce costly [layout reflows](https://developers.google.com/speed/articles/reflow). [Learn more](https://developers.google.com/web/fundamentals/performance/rendering/).', | ||
| requiredArtifacts: ['DOMStats'] | ||
| }; | ||
| } | ||
|
|
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| /** | ||
| * @param {!Artifacts} artifacts | ||
| * @return {!AuditResult} | ||
| */ | ||
| static audit(artifacts) { | ||
| const stats = artifacts.DOMStats; | ||
|
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| /** | ||
| * html > | ||
| * body > | ||
| * div > | ||
| * span | ||
| */ | ||
| const depthSnippet = stats.depth.pathToElement.reduce((str, curr, i) => { | ||
| return `${str}\n` + ' '.repeat(i) + `${curr} >`; | ||
| }, '').replace(/>$/g, '').trim(); | ||
| const widthSnippet = 'Element with most children:\n' + | ||
| stats.width.pathToElement[stats.width.pathToElement.length - 1]; | ||
|
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| // Use the CDF of a log-normal distribution for scoring. | ||
| // <= 1500: score≈100 | ||
| // 3000: score=50 | ||
| // >= 5970: score≈0 | ||
| const distribution = TracingProcessor.getLogNormalDistribution( | ||
| SCORING_MEDIAN, SCORING_POINT_OF_DIMINISHING_RETURNS); | ||
| let score = 100 * distribution.computeComplementaryPercentile(stats.totalDOMNodes); | ||
|
|
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| // Clamp the score to 0 <= x <= 100. | ||
| score = Math.max(0, Math.min(100, score)); | ||
|
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| const cards = [ | ||
| {title: 'Total DOM Nodes', value: stats.totalDOMNodes.toLocaleString()}, | ||
| {title: 'DOM Depth', value: stats.depth.max.toLocaleString(), snippet: depthSnippet}, | ||
| {title: 'Maximum Children', value: stats.width.max.toLocaleString(), snippet: widthSnippet} | ||
| ]; | ||
|
|
||
| return DOMSize.generateAuditResult({ | ||
| rawValue: stats.totalDOMNodes, | ||
| optimalValue: this.meta.optimalValue, | ||
| score: Math.round(score), | ||
| displayValue: `${stats.totalDOMNodes.toLocaleString()} nodes`, | ||
| extendedInfo: { | ||
| formatter: Formatter.SUPPORTED_FORMATS.CARD, | ||
| value: cards | ||
| } | ||
| }); | ||
| } | ||
|
|
||
| } | ||
|
|
||
| module.exports = DOMSize; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,50 @@ | ||
| /** | ||
| * @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'; | ||
|
|
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| const Formatter = require('./formatter'); | ||
| const path = require('path'); | ||
| const fs = require('fs'); | ||
| const html = fs.readFileSync(path.join(__dirname, 'partials/cards.html'), 'utf8'); | ||
|
|
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| class Card extends Formatter { | ||
| static getFormatter(type) { | ||
| switch (type) { | ||
| case 'pretty': | ||
| return result => { | ||
| if (!result || !Array.isArray(result)) { | ||
| return ''; | ||
| } | ||
| let output = ''; | ||
| result.forEach(item => { | ||
| output += ` - ${item.title}: ${item.value}\n`; | ||
| }); | ||
| return output; | ||
| }; | ||
|
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| case 'html': | ||
| // Returns a handlebars string to be used by the Report. | ||
| return html; | ||
|
|
||
| default: | ||
| throw new Error('Unknown formatter type'); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| module.exports = Card; |
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| .cards__container { | ||
| --padding: 16px; | ||
| display: flex; | ||
| flex-wrap: wrap; | ||
| } | ||
| .scorecard { | ||
| display: flex; | ||
| align-items: center; | ||
| justify-content: center; | ||
| flex: 1 1 150px; | ||
| flex-direction: column; | ||
| padding: calc(var(--padding) / 2); | ||
| padding-top: calc(32px + var(--padding) / 2); | ||
| border-radius: 3px; | ||
| margin-right: var(--padding); | ||
| position: relative; | ||
| color: var(--secondary-text-color); | ||
| line-height: inherit; | ||
| border: 1px solid #ebebeb; | ||
| } | ||
| .scorecard-title { | ||
| /*text-transform: uppercase;*/ | ||
| font-size: var(--subitem-font-size); | ||
| line-height: var(--heading-line-height); | ||
| background-color: #eee; | ||
| position: absolute; | ||
| top: 0; | ||
| right: 0; | ||
| left: 0; | ||
| display: flex; | ||
| justify-content: center; | ||
| align-items: center; | ||
| border-bottom: 1px solid #ebebeb; | ||
| } | ||
| .scorecard-value { | ||
| font-size: 24px; | ||
| } | ||
| .scorecard-summary { | ||
| margin-top: calc(var(--padding) / 2); | ||
| } |
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| <ul class="subitem__details cards__container"> | ||
| {{#each this}} | ||
| <div class="subitem__detail scorecard" {{#if snippet}}title="{{snippet}}"{{/if}}> | ||
|
There was a problem hiding this comment. if it will always be the title can we rename snippet to title? There was a problem hiding this comment. I reserved |
||
| <div class="scorecard-title">{{title}}</div> | ||
| <div class="scorecard-value">{{value}}</div> | ||
| </div> | ||
| {{/each}} | ||
| </ul> | ||
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yay for moving out into some new testers! 🎉