Fresh Reads
Source desk · Blog
Josh Comeau
89 entries in the archiveNewest: Oct 20, 2026Official site
- CSS
- React
- JavaScript
Snappy UI Optimization with useDeferredValue
useDeferredValue is one of the most underrated React hooks. It allows us to dramatically improve the performance of our applications in certain contexts. I recently used it to solve a gnarly performance problem on this blog, and in this tutorial, I'll show you how! ⚡ Keep…
CSS in React Server Components
You can’t make an omelette without cracking a few eggs, and when the core React team unveiled their vision for the future of React, some of my favourite libraries got scrambled 😅. In this blog post, we’re going to explore the compatibility issues between React Server Components…
How To Center a Div
Back in the day, centering an element was one of the trickiest things in CSS. As the language has evolved, we’ve been given lots of new tools we can use… But how do we pick the best option? When do we use Flexbox, or CSS Grid, or something else? Let's dig into it. Keep reading.
An Interactive Guide to CSS Grid
CSS Grid is an incredibly powerful tool for building layouts on the web, but like all powerful tools, there's a significant learning curve. In this tutorial, we'll build a mental model for how CSS Grid works and how we can use it effectively. I'll share the biggest 💡 lightbulb…
Understanding the JavaScript Modulo Operator
One of the most commonly-misunderstood operators is Modulo (%). In this tutorial, we'll unpack exactly what this little bugger does, and learn how it can help us solve practical problems. Keep reading.
Making Sense of React Server Components
This year, the React team unveiled something they've been quietly researching for years: an official way to run React components exclusively on the server. This is a significant paradigm shift, and it's caused a whole lot of confusion in the React community. In this tutorial,…
Animated Pride Flags
Happy Pride month! In this tutorial, I'll share a handful of my favourite animation tricks. You'll learn how to build an animated wavy pride flag using CSS keyframes and linear gradients. We'll also see how to make it dynamic using React. 🏳️🌈 Keep reading.
The “const” Deception
The “const” keyword in JavaScript is used to create constants, variables that can't change. Curiously, though, we do seem to be able to edit objects and arrays that are created using “const”. In this tutorial, we're going to dig into the incredibly-important distinction between…
The End of Front-End Development
Large language models like GPT-4 are becoming increasingly capable, at an alarming rate. Within a couple of years, we won't need developers any more! …Or at least, that's the narrative going viral on social media. I'm much more optimistic about what these AI advancements mean…
Common Beginner Mistakes with React
I used to teach React at a local coding bootcamp, and I noticed that students kept getting tripped up by the same handful of things. In this article, we're going to go through 9 of the most dastardly gotchas. I'll show you how to solve these common problems, so you can avoid a…
Data Binding in React
As developers, we don't like working with forms, but they're a critical part of most web applications! In this tutorial, you'll learn exactly how to wire up all of the different form controls in React. Never forget how to data-bind a checkbox or radio button again! Keep reading.
Color Formats in CSS
CSS gives us so many options when it comes to expressing color—we can use hex codes, rgb, hsl, and more. Which option should we choose? This turns out to be a surprisingly important decision! In this article, we'll take a tour of color formats in CSS, and see which option will…
An Interactive Guide to Flexbox
When we truly learn the secrets of the Flexbox layout mode, we can build absolutely incredible things. Fluid layouts that stretch and shrink without arbitrary breakpoints. In this action-packed interactive tutorial, we'll pop the hood on the Flexbox algorithm and learn how to do…
A World-Class Code Playground with Sandpack
No developer blog or technical documentation site is complete without an interactive code playground. The CodeSandbox team recently released a wonderful tool called Sandpack, to help us create these live-updating code editors. In this tutorial, I'll show you how I use it on this…
Understanding useMemo and useCallback
What's the deal with these two hooks?! Lots of devs find them confusing, for a whole host of reasons. In this tutorial, we'll dig deep and understand what they do, why they're useful, and how to get the most out of them. Keep reading.
Why React Re-Renders
In React, we don't update the DOM directly, we tell React what we want the DOM to look like, and React tackles the rest. But how exactly does it do this? In this tutorial, we'll unpack exactly when and why React re-renders, and how we can use this information to optimize the…
Statements Vs. Expressions
One of the most foundational things to understand about JavaScript is that programs are made up of statements, and statements have slots for expressions. In this blog post, we'll dig into how these two structures work, and see how building an intuition about this can help us…
My Wonderful HTML Email Workflow
If you've ever had the misfortune of being tasked with building a template for HTML emails, you know it's tricky business! In this blog post, I share the approach I took to build responsive, client-friendly emails without a single tag. Keep reading.
The Surprising Truth About Pixels and Accessibility
“Should I use pixels or rems?”. In this comprehensive blog post, we'll answer this question once and for all. You'll learn about the accessibility implications, and how to determine the best unit to use in any scenario. Keep reading.
You Don’t Need a UI Framework
As developers, it can be tempting to grab a pre-styled UI framework like Material UI or Bootstrap. Seems like a great way to outsource design and save a bunch of time, right? In my experience, this is an unrealistic expectation, and things don’t quite work out that way. Keep…
The Front-End Developer's Guide to the Terminal
If you want to learn a modern JavaScript framework like React or Angular, you better be familiar with the terminal! So many frameworks and tools assume that you're proficient with it, without ever explaining it. This blog post is your missing manual, covering all of the most…
Understanding Layout Algorithms
As front-end developers, we often learn CSS by focusing on individual properties. Instead, we should focus on how the language uses those properties to calculate layouts. In this blog post, we'll pop the hood on CSS and see how the language is structured, and how to learn it…
Delightful React File/Directory Structure
How should we structure components and other files in our React apps? I've iterated my way to a solution I'm really happy with. In this blog post, I'll share how it works, what the tradeoffs are, and how I mitigate them. Keep reading.
Make Beautiful Gradients
Have you ever noticed that gradients tend to look a little gray and washed-out in the middle? This happens because of a mathematical quirk with RGB colors. Fortunately, we can work around this quirk, and create beautiful, lush, saturated gradients. Keep reading.