TS Congress

TypeScript Congress 2023

Daniel Rowe discusses building a TypeScript-first framework at TypeScript Congress and shares his involvement in various projects. Nuxt is a progressive framework built on Vue.js, aiming to reduce friction and distraction for developers. It leverages TypeScript for inference and aims to be the source of truth for projects. Nuxt provides type safety and extensibility through integration with TypeScript. Migrating to TypeScript offers long-term maintenance benefits and can uncover hidden bugs. Nuxt focuses on improving existing tools and finds inspiration in frameworks like TRPC.

I'll dive into the internals of Nuxt to describe how we've built a TypeScript-first framework that is deeply integrated with the user's IDE and type checking setup to offer end-to-end full-stack type safety, hints for layouts, middleware and more, typed runtime configuration options and even typed routing. Plus, I'll highlight what I'm most excited about doing in the days to come and how TypeScript makes that possible not just for us but for any library author.

Making Magic: Building a TypeScript-First Framework

Daniel Roe

React Summit

React Summit 2023

In this Workshop, the speaker covers various topics related to testing React components. They discuss the importance of testing the contract, behavior, and inputs/outputs of components. The use of React Testing Library and Jest module mocks is highlighted. The speaker also emphasizes the significance of testing user interaction events and external functions. Different testing approaches, best practices, and trade-offs are explored throughout the Workshop.

React Testing Library is a great framework for React component tests because there are a lot of questions it answers for you, so you don’t need to worry about those questions. But that doesn’t mean testing is easy. There are still a lot of questions you have to figure out for yourself: How many component tests should you write vs end-to-end tests or lower-level unit tests? How can you test a certain line of code that is tricky to test? And what in the world are you supposed to do about that persistent act() warning? In this three-hour workshop we’ll introduce React Testing Library along with a mental model for how to think about designing your component tests. This mental model will help you see how to test each bit of logic, whether or not to mock dependencies, and will help improve the design of your components. You’ll walk away with the tools, techniques, and principles you need to implement low-cost, high-value component tests. Table of contents- The different kinds of React application tests, and where component tests fit in- A mental model for thinking about the inputs and outputs of the components you test- Options for selecting DOM elements to verify and interact with them- The value of mocks and why they shouldn’t be avoided- The challenges with asynchrony in RTL tests and how to handle them Prerequisites- Familiarity with building applications with React- Basic experience writing automated tests with Jest or another unit testing framework- You do not need any experience with React Testing Library- Machine setup: Node LTS, Yarn

Designing Effective Tests With React Testing Library

Josh Justice

React 18's concurrent rendering, specifically the useTransition hook, optimizes app performance by allowing non-urgent updates to be processed without freezing the UI. However, there are drawbacks such as longer processing time for non-urgent updates and increased CPU usage. The useTransition hook works similarly to throttling or bouncing, making it useful for addressing performance issues caused by multiple small components. Libraries like React Query may require the use of alternative APIs to handle urgent and non-urgent updates effectively.

React 18! Concurrent features! You might’ve already tried the new APIs like useTransition, or you might’ve just heard of them. But do you know how React 18 achieves the performance wins it brings with itself? In this talk, let’s peek under the hood of React 18’s performance features: - How React 18 lowers the time your page stays frozen (aka TBT) - What exactly happens in the main thread when you run useTransition() - What’s the catch with the improvements (there’s no free cake!), and why Vue.js and Preact straight refused to ship anything similar

React Concurrency, Explained

Ivan Akulov

React Advanced

React Advanced 2022

This transcription provides a brief guide to React rendering behavior. It explains the process of rendering, comparing new and old elements, and the importance of pure rendering without side effects. It also covers topics such as batching and double rendering, optimizing rendering and using context and Redux in React. Overall, it offers valuable insights for developers looking to understand and optimize React rendering.

React is a library for "rendering" UI from components, but many users find themselves confused about how React rendering actually works. What do terms like "rendering", "reconciliation", "Fibers", and "committing" actually mean? When do renders happen? How does Context affect rendering, and how do libraries like Redux cause updates? In this talk, we'll clear up the confusion and provide a solid foundation for understanding when, why, and how React renders. We'll look at: - What "rendering" actually is - How React queues renders and the standard rendering behavior - How keys and component types are used in rendering - Techniques for optimizing render performance - How context usage affects rendering behavior| - How external libraries tie into React rendering

A Guide to React Rendering Behavior

Mark Erikson

The Talk discussed Concurrent React and its impact on app performance, particularly in relation to long tasks on the main thread. It explored parallelism with workers and the challenges of WebAssembly for UI tasks. The concepts of concurrency, scheduling, and rendering were covered, along with techniques for optimizing performance and tackling wasted renders. The Talk also highlighted the benefits of hydration improvements and the new profiler in Concurrent React, and mentioned future enhancements such as React fetch and native scheduling primitives. The importance of understanding React internals and correlating performance metrics with business metrics was emphasized.

Writing fluid user interfaces becomes more and more challenging as the application complexity increases. In this talk, we’ll explore how proper scheduling improves your app’s experience by diving into some of the concurrent React features, understanding their rationales, and how they work under the hood.

Deep Diving on Concurrent React

Matheus Albuquerque

React Summit 2022

This Talk explores the internals of React Fiber and its implications. It covers topics such as fibres and units of work, inspecting elements and parent matching, pattern matching and coroutines, and the influence of coroutines on concurrent React. The Talk also discusses effect handlers in React, handling side effects in components, and the history of effect handlers in React. It concludes by emphasizing the importance of understanding React internals and provides learning resources for further exploration.

I want to provide an in-depth overview of the important concepts behind reconciliation. We'll then explore how React uses the algorithm and go through a few magic words we hear a lot, like coroutines, continuations, fibers, generators, algebraic effects and see how they all relate to React.js.

Inside Fiber: the in-depth overview you wanted a TLDR for

React Summit Remote Edition

React Summit Remote Edition 2021

This workshop on React Hooks Tips explores hooks beyond the basics, covering common mistakes, advanced hooks, creating custom hooks, and the rules of hooks. It demonstrates the use of useState, useEffect, and useContext hooks, as well as creating custom hooks for managing state and performing side effects. The workshop also covers the use of useRef, useReducer, and useLayoutEffect hooks, and provides insights into how React hooks work under the hood. It concludes with the implementation of a provider component and the use of context and reducers to manage complex state in functional components.

The addition of the hooks API to React was quite a major change. Before hooks most components had to be class based. Now, with hooks, these are often much simpler functional components. Hooks can be really simple to use. Almost deceptively simple. Because there are still plenty of ways you can mess up with hooks. And it often turns out there are many ways where you can improve your components a better understanding of how each React hook can be used.You will learn all about the pros and cons of the various hooks. You will learn when to use useState() versus useReducer(). We will look at using useContext() efficiently. You will see when to use useLayoutEffect() and when useEffect() is better. <a href="https://www.froala.com/wysiwyg-editor?pb=1"> </a>

React Hooks Tips Only the Pros Know

Maurice de Beijer

JS Nation

JSNation 2024

The Talk discusses the basics of building a JS engine, highlighting the complexity and feature completeness of existing engines. It emphasizes the possibility of creating a simpler engine tailored to specific use cases and target audiences. The speaker suggests starting anywhere in the process and provides tips on using parser libraries, implementing runtime features, and ensuring correctness through testing. Additionally, the Talk encourages exploring JavaScript standards and engaging with the open-source community.

Modern production-grade JS engines can seem intimidating, but that's not all there is! This lightning talk draws from my past experiences working on hobbyist JS engines, and it will cover the following: - Different angles to approach this seemingly complex task- Things you can learn along the way- Some existing projects that optimize for fun (instead of chasing benchmarks), and what makes them unique You'll see that you don't need a background in compiler design to get started exploring JS engine internals. Most importantly, it's fun!

Building a JS Engine -- For Fun!

Linus Groh

TestJS Summit

TestJS Summit 2023

Today's Talk covered various topics including testing frameworks, browsers, and the challenges faced in testing complex systems. The importance of improving testing setup and productivity was highlighted, along with the principle of least surprise and the need for framework upgrades. The Talk also discussed the different browser engines and their unique features, as well as the benefits of sharing ideas and approaches within the software development community. The session concluded with insights on browser testing and the use of tools like Playwright and WebKit.

<div>Focusing on being where your users are isn't as difficult as you think. A lot of groups out there will tell you that their tool is the best and that even though none of your users use that browser or mobile setup it is fine. In this talk, David will talk about all the differences that come up, why browser vendors are even telling folks not to focus on browser engines or virtual doms, and how the setup of development environments is simple to set up these days. </div>By ignoring the love that is being pushed to developers and testers through the work being done there can be tests that are passing but your users are failing to use your application! Don't worry, David will have the real world examples to show you how broken things are :)

Testing Frameworks, Mobile Frameworks, and Browsers Love Developers and Testers

David Burns

React Advanced 2023

Today's Talk introduces the concepts of hydration and off islands, explores the benefits of islands for enhancing server-side rendered HTML with client-side JavaScript, discusses the lazy approach of re-zoomability and its advantages over traditional hydration, highlights the use of resumability and concurrent React for improved rendering performance, examines the features and concerns of React server components, touches on the co-location of client and server code, and explores future trends in rendering and navigation. The Talk also reflects on past ideas and emphasizes the importance of identifying core metrics for performance optimization.

Our ecosystem can be overwhelming! First, we had the rise of SSR and SSG—and each had its own gigantic pile of frameworks and tools. Then partial hydration enabled us to hydrate only some of our components on the client, which we've seen in React Server Components.  But what about islands? Do they relate at all to Streaming SSR? Moreover, what is resumability, and why do I keep hearing about it? […] Oh, did anyone say rendering on the Edge? Well… There are many approaches out there, and all of them argue that their philosophy is best. In this session, we’ll go over these architecture/rendering patterns, to help shed some light on how some are implemented and the concepts behind them.

Hydration, Islands, Streaming, Resumability… Oh My!

Object proxies are middleware for objects that allow control over input and output. They have various use cases such as controlling data access, adding logging, and handling responses. Implementing object proxies involves transpiling calls into network requests and handling property access and method calls. Handling object proxy traps and errors involves faking object structure, logging target objects and properties, and resolving errors. Making API calls with object proxies involves defining the correct type, making backend calls, and wrapping methods to return promises. Object proxies are widely used in ORMs and RPC libraries and should be explored and experimented with.

You must or must not have heard of object proxies before, but have you ever understood how to use them? What the actual usecase of an object proxy is? In this talk, we will do a deep dive into object proxies, understanding how they work, and the kinds of things you can build using them. We will build higher-order wrappers for existing libraries, and learn how to wrap over them in a type-safe manner.

Unleashing Object Proxies: Building Type-Safe Wrappers for Anything

Akash Joshi

Today's Talk explores TypeScript integration and refactoring, code action handling, the TypeScript server and refactoring process, bug reporting, and the TypeScript protocol and LSP. The Talk discusses how TypeScript is integrated into editors, the role of code action providers, and the communication between the client and server. It also highlights the two-stage process of code actions and the importance of bug reporting. Additionally, it mentions the TypeScript protocol and how it allows for language-specific extensions. LSP is mentioned as a powerful extensibility solution used by various languages.

How can an editor ""automagically"" show type errors when you create a single TypeScript file without running ""npm install typescript"" or having a tsconfig.json file? Is a completion list build by your coding editor, TypeScript itself, or some other mysterious being? What is TSServer? In this talk I will give you an overview of how the TypeScript server communicates with IDEs and other editors, delivering rich language features without ever running tsc.

How TypeScript is integrated in your editor

Maria Solano

The TC59 Type Annotations proposal, also known as Types with Comments, introduces the ability to run typed code in JavaScript. It aims to bring TypeScript back into JavaScript and create a separation between type system and runtime. TypeScript's popularity is on par with JavaScript, raising concerns about the influence of Microsoft. The proposal progresses by addressing runtime interaction and token soup in type specifications. Research, community involvement, and quantifying the effects of supporting this comment style are important goals.

A deep dive into the proposal which could de-fork TypeScript and bring all us users back to being "JavaScripters, but with some TypeScript types." We'll cover the author's motives, how it could work, why now and how it is going.ort

What is "TC39: Type Annotations" aka the Types as Comments proposal

Orta Therox

This Talk explores the power of Abstract Syntax Trees (ASTs) in software development. It covers the use of ASTs in maintaining React examples, automating dependency identification, and introducing generic typing. The Talk also discusses using ASTs to reason about and generate code, as well as their application in building ESLint plugins and code mods. Additionally, it highlights resources for exploring ASTs, testing AST scripts, and building Babel plugins.

When refactoring large code bases, Find and Replace even with Regexes, can only get you so far. When that fails don’t fallback to painful manual updates instead reach for Abstract Syntax Trees (AST). In this session we introduce AST’s and show how they can be used to reason about / generate code. You will leave with a greater understanding of how you can automatically update code and new insights into how code linters work under the hood.

Supercharged Code Refactoring via Abstract Syntax Trees

Stephen Cooper

The islands architecture is a new way to build websites with low or no JavaScript, using libraries like Astro and Fresh. Server-side rendering improves SEO and loading times, but can still result in large JavaScript payloads. Hydration allows for islands of interactivity, loading only necessary JavaScript. Astro is a framework for implementing the islands architecture, supporting multiple libraries like React and SolidJS. It enables progressive migration between frameworks and integration of different libraries in the same project.

An introduction to the emerging islands architecture which can significantly improve the performance of your apps.

Astro & Fresh - Understanding the Islands Architecture

Arpit Bharti

This Talk discusses the process of recreating Age of Empires II in React. The speaker shares their inspiration for the project and explores different approaches to game development using React. They demonstrate how to create an isometric grid, enable scrolling, and render units. The Talk also covers handling unit clicks and implementing right-click movement, as well as techniques for making React render more consistently. The speaker concludes by highlighting the value of exploring different tools and approaches in software development.

How better to learn about the capabilities of a technology than to do something it was expressly not designed for? What can we learn about the square peg as we mercilessly shove it into the triangular hole? In an attempt to rebuild Age of Empires 2 using React we'll learn about the limitations and possibilities of the tool we use everyday.

Building Age of Empires 2 in React

Joe Hart

This talk focuses on arrows and their unique features in diagramming tools. It explores the challenges of arrow positioning and connector selection, particularly with irregular shapes. The talk also discusses alternative arrow intersections and curved lines, as well as the challenges of creating curved arrows. The speaker presents a method for creating arrows and moving handles that always look good. The talk concludes with an invitation to try out the new version of Teal Draw and follow the speaker on Twitter for more arrow content.

Love linking lines? Join me in considering the humble arrow as both a programming problem and a user experience challenge. In this talk, I'll present the many complex problems and solutions that I've encountered when working with arrows in my open source library perfect-arrows and later in tldraw (tldraw.com). With a narrow scope and plenty of animations to guide the way, we'll look at intersections, arrow heads, arrow head angles, and all of the different user interface issues behind authoring and adjusting arrows between shapes, other shapes, and points.

Arrows (At Length)

Steve Ruiz

Today's Talk dives deep into React Native development, exploring the development process, JavaScript-native communication, and app deployment. It highlights the app building process, the React Native Run iOS command, and development gestures for efficient execution. The Talk also emphasizes the recommended process for starting and testing your app, as well as handling the 'red screen of death' error by installing missing libraries and understanding the role of the UI manager in creating native views.

How do you start your app on your simulator in the morning? Do you always run react-native run-ios? If so, you might be wasting a lot of time. Let’s check out together what a React Native app looks like under the hood. It will help us to be more efficient on a daily basis. We’ll identify the shortest steps to execute daily actions, like starting our apps as fast as possible (no more unnecessary compilations of native modules!), or dealing with pesky red errors that metro throws at us.

What Happens When You Build Your App

Charlotte Isambert

This Talk discusses React performance and how re-renders can affect it. It highlights common mistakes and misconceptions, such as the overuse of useMemo and useCallback hooks. The importance of React.memo in preventing unnecessary child component re-renders is emphasized. Creating components in render functions is identified as a major performance killer, and the benefits of moving state down and wrapping state around children are explained. The Talk also covers optimizing component rendering through memoization and provides a recap of the key points.

React is a fantastic tool to implement complicated applications fast, we all know it. But are they going to be fast when implemented fast? Let’s talk about re-renders and their danger in react: how easy it is to make a mistake, why some small mistakes can have a huge downstream effect, and how to avoid and prevent them.This is a deep-dive type of talk, that focuses on why React components re-render, what kind of performance impact it can have, and what to do about it

Let’s Talk about Re-renders

Nadia Makarevich

TypeScript Congress 2022

This workshop covers advanced TypeScript types and features such as strict mode, type validation, error handling, and type mappings. It explores techniques to improve code reliability and prevent errors. Topics include treating elements as never being null, deriving TypeScript type definitions from schemas, using read-only types to enforce immutability, and utilizing type mappings like omit and pick. The workshop also emphasizes the importance of type safety, type readability, and exhaustiveness testing. Overall, it provides practical insights to enhance the reliability and type safety of TypeScript code.

If you're looking to get the most out of TypeScript, this workshop is for you! In this interactive workshop, we will explore the use of advanced types to improve the safety and predictability of your TypeScript code. You will learn when to use types like unknown or never. We will explore the use of type predicates, guards and exhaustive checking to make your TypeScript code more reliable both at compile and run-time. You will learn about the built-in mapped types as well as how to create your own new type map utilities. And we will start programming in the TypeScript type system using conditional types and type inferring. Are you familiar with the basics of TypeScript and want to dive deeper? Then please join me with your laptop in this advanced and interactive workshop to learn all these topics and more. You can find the slides, with links, here: <a href="http://theproblemsolver.nl/docs/ts-advanced-workshop.pdf">http://theproblemsolver.nl/docs/ts-advanced-workshop.pdf</a> And the repository we will be using is here: <a href="https://github.com/mauricedb/ts-advanced">https://github.com/mauricedb/ts-advanced</a>

Advanced TypeScript types for fun and reliability

React Advanced 2021

In this Talk, the speaker discusses the importance of planning and maintaining UIs in React using state machines. They highlight the need to consider user experience and plan for performance and maintainability. The challenges of handling multiple UI states are addressed, and the benefits of using finite state machines are explained. The speaker demonstrates how to implement transitions and update the UI using a React state machine. They emphasize the benefits of state machines in handling errors, avoiding state explosions, and improving collaboration between designers and developers.

One of the biggest pain points when developing an app is the tricky business of managing state, race conditions, etc. Finite state machines can help eliminate such bugs entirely while providing a welcome, structured way to build components. Looks cool? Let’s build one, it’s even cooler! <a href="https://www.froala.com/wysiwyg-editor?pb=1"> </a>

#deep dive