Stop using Knex.js (and earn $30)
This is true about any SQL query builder. I chose to use knex.js as an example because it is the most popular SQL query builder in the Node.js ecosystem and we need an example. tl;dr; Knex.js (and other query builders) was designed to be a building block for ORMs; it does not add value when majority of the query is static. If you are evaluating alternative to Knex.js, I have since published anothe
When a rewrite isn’t: rebuilding Slack on the desktop
Conventional wisdom holds that you should never rewrite your code from scratch, and that’s good advice. Time spent rewriting something that already works is time that won’t be spent making our customers working lives simpler, more pleasant, and more productive. And running code knows things: hard-won knowledge gained through billions of hours of cumulative usage and tens of thousands of bug fixes.
Modern Script Loading - JASON Format
Serving the right code to the right browsers can be tricky. Here are some options. Serving modern code to modern browsers can be great for performance. Your JavaScript bundles can contain more compact or optimized modern syntax, while still supporting older browsers. The tooling ecosystem has consolidated on using the module/nomodule pattern for declaratively loading modern VS legacy code, which p
Weak references and finalizers · V8
Show navigation Generally, references to objects are strongly held in JavaScript, meaning that as long you have a reference to the object, it won’t be garbage-collected. const ref = { x: 42, y: 51 }; // As long as you have access to `ref` (or any other reference to the // same object), the object won’t be garbage-collected.Currently, WeakMaps and WeakSets are the only way to kind-of-weakly referen
Is postMessage slow? — surma.dev
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
Algebraic Effects for the Rest of Us — overreacted
Algebraic Effects for the Rest of UsJuly 21, 2019 Have you heard about algebraic effects? My first attempts to figure out what they are or why I should care about them were unsuccessful. I found a few pdfs but they only confused me more. (There’s something about academic pdfs that makes me sleepy.) But my colleague Sebastian kept referring to them as a mental model for some things we do inside of
Implementing an efficient LRU cache in JavaScript
Where we discover how to harness the power of JavaScript's typed arrays to design our very own low-cost pointer system for fixed-capacity data structuresTable of Contents The LRU cacheImplementing a LRU cacheDoubly-linked listsLRU Cache list operationsImplementing doubly-linked lists in JavaScriptA custom pointer systemIs it really worth the hassle?Concluding remarksMiscellanyAbout evictions & spl
The cost of JavaScript in 2019 · V8
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
Object.fromEntries · V8
Object.fromEntries is a useful addition to the built-in JavaScript library. Before explaining what it does, it helps to understand the pre-existing Object.entries API. Object.entries #The Object.entries API has been around for a while. Chrome: supported since version 54Firefox: supported since version 47Safari: supported since version 10.1Node.js: supported since version 7Babel: supported For each
Array.prototype.flat and Array.prototype.flatMap · V8
Show navigation Array.prototype.flat #The array in this example is several levels deep: it contains an array which in turn contains another array. const array = [1, [2, [3]]]; // ^^^^^^^^^^^^^ outer array // ^^^^^^^^ inner array // ^^^ innermost arrayArray#flat returns a flattened version of a given array. array.flat(); // → [1, 2, [3]] // …is equivalent to: array.flat(1); // → [1, 2, [3]]The defa
Bringing service workers to Google Search | web.dev
Background Search for just about any topic on Google, and you're presented with an instantly recognizable page of meaningful, relevant results. What you probably didn't realize is that this search results page is, under certain scenarios, served by a powerful piece of web technology called a service worker. Rolling out service worker support for Google Search without negatively impacting the perfo
How to Use the Web Share API | CSS-Tricks
Get affordable and hassle-free WordPress hosting plans with Cloudways — start your free trial today. The Web Share API is one that has seemingly gone under the radar since it was first introduced in Chrome 61 for Android. In essence, it provides a way to trigger the native share dialog of a device (or desktop, if using Safari) when sharing content — say a link or a contact card — directly from a w
Unpacking hoisting
The following sections describe the behavior of some of these constructs in more detail. const and let: temporal dead zone # For JavaScript, TC39 needed to decide what happens if you access a constant in its direct scope, before its declaration: { console.log(x); // What happens here? const x; } Some possible approaches are: The name is resolved in the scope surrounding the current scope. You get
Enabling Modern JavaScript on npm - JASON Format
Modern JavaScript syntax lets you do more with less code, but how much of the JavaScript we ship to users is actually modern? For the past few years we’ve been writing modern JavaScript (or TypeScript), which is then transpiled to ES5 as a build step. This has let the “state of the art” of JavaScript move forward at a faster pace than could have otherwise been achieved while supporting older brows
Dive into IndexedDB
Dive into IndexedDB IndexedDB is one of the storage capabilities introduced into browsers over the years. Here's an introduction to IndexedDB, the Database of the Web supported by all modern Browsers Introduction to IndexedDB Create an IndexedDB Database How to create a database Adding data into a store Adding data when the store is created, initializing it Adding data when the store is already cr
Improving third-party web performance at The Telegraph
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
イメージで伝われ！図解JavaScriptの非同期処理 - メモを揉め
ものすごい久しぶりのブログ更新になってしまいましたが、今回はJavaScriptの非同期処理について書いてみたいと思います。 このテーマはうまく説明できない部分が毎回ちょいちょいあるのですが、こうしてまとめることで頭の中が整理されていくということもあるので、最後まで頑張りたいと思います。 前提としてブラウザの実装の詳細や仕様については分からない部分も多いため、間違っている部分もあるかもしれません。 もし、お気づきの点などありましたら、教えていただけると助かります。 目次 目次 同期と非同期の比較その1 同期的実行 非同期的実行 同期的実行 非同期的実行 同期と非同期の比較その2 同期的実行 非同期的実行 並行処理と並列処理 非同期API 非同期APIの特徴 その他の非同期API addEventListenerに渡したコールバックの同期的実行 非同期処理のユースケース コールバック Pro
WebAssembly at eBay: A Real-World Use Case
From the time it was announced, WebAssembly caused a huge buzz in the front-end world. The web community readily embraced the idea of taking code written in programming languages other than JavaScript and running that code in the browser. Above all WebAssembly consistently guarantees native speeds much faster than JavaScript. At eBay, we were no different. Our engineers were very excited about thi
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Snyk research team discovers severe prototype pollution security vulnerabilities affecting all versions of lodash | Snyk
An introduction to the MediaRecorder API