The cost of JavaScript in 2019Published 25 June 2019 · Tagged with internals parsingNote: If you prefer watching a presentation over reading articles, then enjoy the video below! If not, skip the video and read on.Long Tasks</a> that can keep the main thread busy and can push out how soon pages are interactive. Post-download, script execution time is now a dominant cost.</ul><li><strong>Avoid large inline scripts</strong> (as they’re still parsed and compiled on the main thread). A good rule of thumb is: if the script is over 1 kB, avoid inlining it (also because 1 kB is when <a href=/blog/code-caching-for-devs>code caching</a> kicks in for external scripts).</ul><h2 id=download-execute tabindex=-1>Why does download and execution time matter? <a href=#download-execute class=bookmark>#</a></h2><p>Why is it important to optimize download and execution times? Download times are critical for low-end networks. Despite the growth in 4G (and even 5G) across the world, our <a href=/cats-d8c4vu/www.youtube.com/watch?v=D1UJgiG4_NI">“Parsing JavaScript in zero* time”</a> as presented by Leszek Swirski at BlinkOn 10.</figcaption></figure><h2 id=how-do-these-changes-reflect-what-you-see-in-devtools%3F tabindex=-1>How do these changes reflect what you see in DevTools? <a href=#how-do-these-changes-reflect-what-you-see-in-devtools%3F class=bookmark>#</a></h2><p>In addition to the above, there was <a href="/cats-d8c4vu/www.youtube.com/embed/ff4fgQxPaO0?start=130" width=560>// replace the first image we see with a cat document.images[0].src = 'http://thecatapi.com/api/images/get?format=src&type=gif'; // replace the google logo with a cat document.getElementById('lga').innerHTML = ''; Follow Lee on X/Twitter - Father, Husband, Serial builder creating AI, crypto, games & web tools. We are friends :) AI Will Come To Life! Check out: eBank.nz (Art Generator) | Netwrck.com (AI Tools) | Text-Generator.io (AI API) | BitBank.nz (Crypto AI) | ReadingTime (Kids Reading) | RewordGame | BigMultiplayerChess | WebFiddle | How.nz | Helix AI Assistant