The speed and consistency at which the JavaScript language has evolved over the past years is tremendous. While in the past it was used primarily on the client side, it has taken a very important and respected place in the world of building services and server-side tools. JavaScript has evolved to a point where it is not only possible to create faster applications but also to run servers within browsers.

In this overview of her JavaScript Chapter in the 2021 Web Almanac, Nishu Goel dives deeply into HTTPArchive data on just how JavaScript is used in the real world.

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Decorators have been one of the most anticipated new features in JavaScript for the better part of a _decade_ now. After a long haul and a lot of debate, they’ve finally advanced to Stage 3, and are moving toward being accepted in the language. In this talk, we’ll dig into the history of this proposal, discuss why it has been so difficult to design and fraught with setbacks, and check out how the latest iteration works in detail.

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The 'Change Array by Copy' TC39 proposal has reached stage 3. This talk will cover the benefits of the proposed methods and review the details that have gone into their design.

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Today, even a static site is full of JavaScript to add menus, interactivity, and third-party analytics scripts such as Google Tag Manager, which can drastically lower your Lighthouse score. Partytown provides a way to improve performance scores by running third-party scripts from a web worker.

A JavaScript based site consists of two sources of slow down, the site itself and third-party scripts. Partytown is going to solve the the latter, by removing third party scripts from the main thread of your website.

The philosophy is that the main thread should be dedicated to your code, and any scripts that are not required to be in the critical path should be moved to a web worker. Main thread performance is, without question, more important than web worker thread performance.

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Garbage Collection (GC) in JavaScript is supposed to simplify and automate memory management. But it turns out that there are various scenarios where GC can get in the way, and avoiding resource leaks becomes challenging. In order to overcome such issues, the ECMAScript standard includes WeakMap and WeakSet. More recently, ES2021 introduced WeakRef and FinalizationRegistry for even more fine-grained control, and they are already supported by all modern browsers. In this presentation I explain what these are, why they're needed, and provide concrete usage examples and best practices.

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We all know promises and async/await are the official ways to write async code in JavaScript. But working with promises and async functions can be tricky. In this talk, I'll walk through promises and async/await from base principles, with an emphasis on effective mental models on topics ranging from "how do promises work?" to "does a given package support promises?

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A major earthquake has hit TC39, the JavaScript standards committee. A proposal for adding type annotations to JavaScript has just landed in the committee, and has been approved for Stage 1. What is this proposal all about? How did it come to be? What is the motivation behind it? What are its pros and cons? Why are some people excited about it, some wary, some angry, and some afraid? As one of the writers of this proposal, I will delve into the details of the proposal, and try to answer all the questions above.

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People treat function composition with a great deal of respect in the functional programming community. But if you look at what function composition is, you might be left confused. After all, it’s not a complex idea. We take two functions and smush them together. What’s the big deal?

Even if you’re comfortable with composition, you’ll find people use many variations. In different libraries, you’ll find compose(), flow() and pipe() (sometimes with different names). What’s the difference? And what are they useful for?

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Developers spend up to half their time debugging software, but many don't have an effective process or understanding of debugging tools. JS frameworks add to debugging complexity. This talk outlines how to approach debugging apps built with JS frameworks like React, Angular, and Vue. We'll discuss process, tools, and identifying common framework-related bugs.

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This talk will walk you through writing a module in TypeScript that can be consumed by users of Deno, Node, and browsers. I will walk through how to set up formatting, linting, and testing in Deno, and then how to publish your module to deno.land/x and npm. I will also start out with a quick introduction on what Deno is

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As JavaScript applications get more and more complex, improved performance is on everyone's minds. In the meantime, computers are evolving: CPU hardware is scaling with multi-core, big.LITTLE rather than frequency.

Where does JavaScript stand in this new world and how can it adapt? What role will WebAssembly play in this? What are the current tools and techniques developers can use to develop performant JavaScript applications and what is in store for the future? These are the few questions that we will answer in the course of this presentation.

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JavaScript is everywhere. There are JavaScript runtimes on the client, on the server, and at various locations between, and while TC-39 has provided us with a number of powerful built-in language features, modern applications on the Web require much more than just what the language gives us. The collection of Web Platform APIs that have been developed is continually growing, most of which only apply to the narrow sets of use cases in certain types of browser-based applications. But there is a subset of Web Platform APIs that are becoming ubiquitous across every JavaScript runtime. In this talk, I will introduce the JavaScript stdlib and the ongoing efforts to define it.

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