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Published: May 4, 2020 Optimizing for quality of user experience is key to the long-term success of any site on the web. Whether you're a business owner, marketer, or developer, Web Vitals can help you quantify the experience of your site and identify opportunities to improve. Overview Web Vitals is an initiative by Google to provide unified guidance for quality signals that are essential to deliv
There is no faster (pun intended) way to slow down a site than to use a bunch of JavaScript. The thing about JavaScript is you end up paying a performance tax no less than four times: The cost of downloading the file on the network The cost of parsing and compiling the uncompressed file once downloaded The cost of executing the JavaScript The memory cost The combination is very expensive. And we a
If you search for any JavaScript performance advice, a very popular recommendation is to avoid the delete operator. Today, this seems to be good advice, but why should it be vastly more expensive to delete a property than to add it? The goal of my internship at Apple this winter was to improve the performance of the delete operator in JavaScriptCore. This has given me the opportunity to learn abou
Slow Code HATES him! Optimising a web app from 1 to 60fps This post explores my experience optimising a web app through iterative improvement. The app uses Svelte, but you don’t need any prior experience, and most of what I discuss applies to any web app. It follows on from Embrace your Obsessions! so if you want to learn more about Minesweeper and the context of this post, give it a read. After m
Home Ideas Writing & Speaking About Bio, Talks, Photos Subscribe RSS, Newsletter, Mixtape I was listening to the Official AWS Podcast’s episode on Observability and was struck by how much thought has been given towards improving tools for investigating when things go wrong. I realized that we could probably have something to learn by applying this lens to the JavaScript developer experience. Note:
Doug Sillars (@dougsillars) is a leading mobile developer advocate and evangelist. He is widely known as an expert in mobile application architecture, especially when it comes to performance. Doug has worked with thousands of developers around the world, helping them improve the speed, battery life and customer satisfaction of their applications (both native and web). The author of O'Reilly's "Hig
Because the JSON grammar is much simpler than JavaScript’s grammar, JSON can be parsed more efficiently than JavaScript. This knowledge can be applied to improve start-up performance for web apps that ship large JSON-like configuration object literals (such as inline Redux stores). Presented by: Mathias Bynens - https://goo.gle/2Oh2tq6 More info → https://goo.gle/33czWGH #ChromeDevSummit All S
[ { "name": "", "entryType": "layout-shift", "startTime": 210.78500000294298, "duration": 0, "value": 0.0001045969445437389, "hadRecentInput": false, "lastInputTime": 0 } ] In this example there was a single very tiny shift of 0.01% at 210ms. Knowing the time and severity of the shift is useful to help narrow down what could have caused the shift. Let's turn back to WebPageTest for a lab environme
At Google I/O 2019 Mariko, Jake, and I shipped PROXX, a modern Minesweeper-clone for the web. Something that sets PROXX apart is the focus on accessibility (you can play it with a screenreader!) and the ability to run as well on a feature phone as on a high-end desktop device. Feature phones are constrained in multiple ways: Weak CPUs Weak or non-existent GPUs Small screens without touch input Ver
This week saw the conclusion of a project that I've been shepherding on and off since September of last year. The goal was for the initialisation of our asynchronous JavaScript pipeline (at the time, 36 kilobytes in size) to fit within a budget of 28 KB – the size of two 14 KB bursts of Internet packets. In total, the year-long effort is saving 4.3 Terabytes a day of data bandwidth for our users'
Toggle dark mode No, not really. (It depends.) What does “slow” mean? I said it before, and I will say it again: If you didn’t measure it, it is not slow, and even if you measure it, the numbers are meaningless without context. That being said, the fact that people will not even consider adopting Web Workers because of their concerns about the performance of postMessage(), means that this is worth
Show navigation Note: If you prefer watching a presentation over reading articles, then enjoy the video below! If not, skip the video and read on. “The cost of JavaScript” as presented by Addy Osmani at #PerfMatters Conference 2019.One large change to the cost of JavaScript over the last few years has been an improvement in how fast browsers can parse and compile script. In 2019, the dominant cost
別件で V8 の JIT コードの逆アセンブルを眺めている時に気づいたのですが、JavaScriptで new Array(100) という形で配列を作るのは、高速化の観点から言うと V8 においては避けるべき書き方です。 高速化を求める方は、 new Array() や [] で作成して Array#push で追加していくのが良いでしょう。この記事では、その理由を説明します。 今回の記事は、以下の V8 のブログ記事を参考にしております。 https://v8.dev/blog/elements-kinds 「詰まった配列(Packed Array)」と「穴あき配列(Holey Array)」 v8 は内部的に、その配列がどういうタイプの配列であるかの状態を記録しており、その情報を利用して最適化を適用します。状態は内部的には21個あるのですが、今回話題にするのは、その中でも「詰まってい
At The Telegraph we’re currently going through a process of rebuilding our public-facing website. This gives us the opportunity to take learnings from the existing build but also write some of the code from scratch. You can see our progress so far on pages such as Gaming and Culture. We can monitor the impact this has on metrics across usability, performance and accessibility. We’re incredibly pas
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