Created
November 28, 2016 16:20
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Demonstrating how asynchronous code can let the browser render the UI in between propagated async callbacks
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| const array = [1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]; | |
| function handleArrayValue(v) { | |
| console.log(`Handling ${v}`); | |
| for (let i = 0; i < 15000; ++i) { | |
| for (let j = 0; j < i; ++j) { | |
| // Nothing! | |
| } | |
| } | |
| } | |
| function asyncForEach(cb) { | |
| this.forEach(v => { | |
| setTimeout(_ => { | |
| cb(v); | |
| }, 0); | |
| }); | |
| } | |
| Array.prototype.asyncForEach = asyncForEach; | |
| document.querySelector('#asyncTrigger').addEventListener('click', evt => { | |
| array.asyncForEach(handleArrayValue); | |
| }); | |
| document.querySelector('#syncTrigger').addEventListener('click', evt => { | |
| array.forEach(handleArrayValue); | |
| }); |
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>Async For Each</title> | |
| <link rel="stylesheet" href="master.css"> | |
| <link href="https://fonts.googleapis.com/icon?family=Roboto" rel="stylesheet"> | |
| </head> | |
| <body> | |
| <h1>UI Render Blocking Example</h1> | |
| <div id="expander"></div> | |
| <div id="lorem"> | |
| <button id="syncTrigger" type="button" name="button">Synchronous <code>.forEach(...)</code></button> | |
| <button id="asyncTrigger" type="button" name="button">Asynchronous <code>.forEach(...)</code></button> | |
| <p style="margin-top: 10px"> | |
| "Sed ut perspiciatis unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, | |
| totam rem aperiam, eaque ipsa quae ab illo inventore veritatis et quasi architecto beatae vitae dicta | |
| sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia | |
| consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui | |
| dolorem ipsum quia dolor sit amet, consectetur, adipisci velit, sed quia non numquam eius modi tempora | |
| incidunt ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum | |
| exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem | |
| vel eum iure reprehenderit qui in ea voluptate velit esse quam nihil molestiae consequatur, vel illum qui | |
| dolorem eum fugiat quo voluptas nulla pariatur?" | |
| </p> | |
| </div> | |
| <script src="asyncForEach.js" defer></script> | |
| </body> | |
| </html> |
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| * { | |
| margin: 0; | |
| padding: 0; | |
| box-sizing: border-box; | |
| font-family: Roboto, sans-serif; | |
| } | |
| h1 { | |
| text-align: center; | |
| } | |
| #expander { | |
| background: firebrick; | |
| width: 200px; | |
| height: 200px; | |
| margin: 80px auto; | |
| transition: transform 2s; | |
| } | |
| #expander:hover { | |
| transform: rotate(180deg); | |
| } | |
| #lorem { | |
| width:90%; | |
| max-width: 500px; | |
| margin: 0 auto | |
| } | |
| button { | |
| padding: 10px; | |
| } |
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