WorkerDOM: Concurrency for JavaScript programming with the DOM
Better tree shaking with deep scope analysis
Here’s my project in GSoC 2018: Improve tree-shaking for webpack, a widely used JS code bundler. IntroductionTree-shaking, a supporting feature for DCE(dead code elimination) to help DCE on cross-module usage, is a crucial feature for a bundler. It's especially true for JS. Reducing the bundle size means reducing the network cost each time a bundle is delivered for web application. Project on Gith
Variable Scope in Modern JavaScript
It often surprises me when speaking to other JavaScript developers how many are unaware of how variable scope works in the language they code in. By scope we are talking about the visibility of variables in our code; or in other words which parts of the code can access and modify a variable. I regularly find people declaring variables with var in the middle of code, not knowing how JavaScript will
ちゃんと理解するCode Splitting - Qiita
Deleted articles cannot be recovered. Draft of this article would be also deleted. Are you sure you want to delete this article? Code Splitting、サボってきたのですが、必要になりそうだったので真面目に調べてみました。 これからCode Splittingやりたい方の入口的な役割になれれば幸いです。 Code Splittingとはなにか Code Splittingはその名の通り「コードを分割すること」を指します。分割されたコードはユーザのアクションに応じて非同期に読み込まれます。 ちなみにWebpackでentry point分けることとかもCode Splittingと言えばそうなのですが、本記事では触れません。また、別にSPAでなくともCode
The Cost Of JavaScript In 2018
Update: The Cost Of JavaScript In 2019 is now available to read. Building interactive sites can involve sending JavaScript to your users. Often, too much of it. Have you been on a mobile page that looked like it had loaded only to tap on a link or tried to scroll and nothing happens? Byte-for-byte, JavaScript is still the most expensive resource we send to mobile phones, because it can delay inter
Logging Activity With The Web Beacon API — Smashing Magazine
The Beacon API is a lightweight and efficient way to log information from a web page back to a server. It is used for sending small amounts of data to a server without waiting for a response. Think of it like a postcard sent home when on vacation. You put a small amount of data on it, put it in the mailbox, and you don’t expect a response. In this article, Drew McLellan will help you find out how
Array.prototype.sort について
JavaScript の配列にはsortメソッドがあり配列のソートを実行することができるけど、この配列のソートの中の実装はどうなっているのかという話。v8 における配列ソートについての記事が大変参考になりました。 Chrome(V8)の実装はarray.jsにあり、配列の要素数が 10 以下の場合はInsertion sortを使い、それ以上の場合はQuicksortを利用する。Insersion sort の計算量は O(n^2)であるけど、少ない要素数の場合は Quicksort などより高速になるらしい。直近の commmitを見る限りだと、Chrome 69 か 70 あたりでTimsortに置き換えるつもりらしい。Timsort は average が O(n log n)で、最悪でも O(n log n)の計算量で済む。Quicksort を TimSort に置き換えるつもり
Page Lifecycle API | Web Platform | Chrome for Developers
Modern browsers today will sometimes suspend pages or discard them entirely when system resources are constrained. In the future, browsers want to do this proactively, so they consume less power and memory. The Page Lifecycle API provides lifecycle hooks so your pages can safely handle these browser interventions without affecting the user experience. Take a look at the API to see whether you shou
What's Happening With the Pipeline (|>) Proposal? · Babel
With the release of babel@7.0.0-beta52, we introduced a new required configuration flag to @babel/plugin-proposal-pipeline-operator, a breaking change for the pipeline operator. To clear up any confusion, let's take a look at the pipeline proposal and why we needed to introduce this configuration option. Current Status The pipeline operator was originally introduced by Gilbert Garza, providing a
An adventure in sparse arrays
I offered to coach JavaScript recently, and an exercise I dreamt up was to implement every array (prototype) method, and write tests that they work. Since I'd come down with tonsillitis which apparently comes with a full on bedridden fever, I thought I'd have a go myself. And I learnt a few things along the way. Today, I wanted to share the swiss cheese wonder of sparse arrays! (see what I did the
face-api.js — JavaScript API for Face Recognition in the Browser with tensorflow.js
I am excited to say, that it is finally possible to run face recognition in the browser! With this article I am introducing face-api.js, a javascript module, built on top of tensorflow.js core, which implements several CNNs (Convolutional Neural Networks) to solve face detection, face recognition and face landmark detection, optimized for the web and for mobile devices. As always we will look into
Audio worklet design pattern | Blog | Chrome for Developers
The previous article on Audio Worklet detailed the basic concepts and usage. Since its launch in Chrome 66 there have been many requests for more examples of how it can be used in actual applications. The Audio Worklet unlocks the full potential of WebAudio, but taking advantage of it can be challenging because it requires understanding concurrent programming wrapped with several JS APIs. Even for
E2EテストをPhantomJSから、Puppeteer + Headless Chromeへ移行しました - LCL Engineers' Blog
Webエンジニアの森脇です。LCLでは、以前より「Capybara + PhantomJS」でE2Eテストを行っていましたが、「Puppeteer + Headless Chrome」へ変更しました。 元々は、軽くPuppeteerを触ってみるだけのつもりでしたが、できが良く本格的にE2Eテストへ導入することにしました。 本記事では、変更の経緯や、PuppeteerでE2Eテストを実装する上でのTIPSを紹介します。なお、Capybara + PhantomJSを利用したE2Eテストは、以下の記事でご紹介しております。 techblog.lclco.com 変更の経緯 PhantomJSは古めのWebkitをベースにしているため、一部のCSSがうまく適用されず、Headless Chromeへ移行を以前より考えていました。そんな中、PhantomJSの開発が終了したこともあり、移行すること
Understanding Jest Mocks
Mocking is a technique to isolate test subjects by replacing dependencies with objects that you can control and inspect. A dependency can be anything your subject depends on, but it is typically a module that the subject imports. For JavaScript, there are great mocking libraries available like testdouble and sinon, and Jest provides mocking out of the box. Recently, I joined Jest as a collaborator
社内勉強会 TechLunch で"JavaScript AST ことはじめ"という発表をしました | MEDLEY Developer Portal
2018-06-22社内勉強会 TechLunch で"JavaScript AST ことはじめ"という発表をしましたみなさん、こんにちは。開発本部エンジニアの平木です。こちらのブログの投稿自体はほぼ 1 年ぶりになりそうな勢いですが、みなさまお元気でしょうか? 弊社で定期的に開催してる社内勉強会 TechLunch で自分の順番が回ってきたため、どうしようか迷った末にJavaScript AST ことはじめという発表をしたので、そのことについて書いていきます。 なぜ JavaScript AST について話そうと思ったのか現在、弊社のエンジニアメンバーのバックグラウンドで一番多数派なのは「元サーバサイドエンジニア」です。もちろん、業務ではサーバサイド・フロントエンド・ネイティブアプリとバックグラウンドに関わらず、必要に応じて分け隔てなく開発しています。 とはいえ、ちゃんとサービス開発自体
React Native at Airbnb – Airbnb Engineering & Data Science – Medium
UpdateThis article was published in 2018 and reflects the state of React Native at the end of 2017. When using these articles to make decisions about your business, please use discretion. Any technical points should be revalidated because the maturity and size of the ecosystem was significantly different back then. Any organizational points should also be considered within the context, size, and c
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The Definitive TypeScript Guide - Blog | SitePen
Compiler in JavaScript using ANTLR
Connection-Aware Components
react-ideal-image/introduction.md at master · stereobooster/react-ideal-image
