A few readers wrote in to say that the React Can Update State During Render email last week made no sense. Here's a better explanation.
July 7th, 2023

An unexpected feature of React: updating state during render. It's a UX and performance optimization
June 30th, 2023

Performance lives in the unlikliest of places. Follow the metrics.
January 31st, 2023

A way to embed tweets in static sites with full pre-renders and live updates using just 9kB of client-side JavaScript, 2 HTTP requests, and full reader privacy ✌️
October 26th, 2022

People on twitter loved this trick I learned from a coworker's pull request the other day. You might like it too.
April 22nd, 2022

The pros and cons of different approaches to writing resilient code that handles partial failures
April 4th, 2022

Or how we took an API endpoint from 16s to 3s.
February 4th, 2022

The cult of TDD leads you down a dark and stormy path towards brittle code with a false sense of security. But there is a better way. A sweet spot between unit and heavy integration.
December 21st, 2021

Every null or undefined check doubles the number of tests you need 😱
December 10th, 2021

wanna see the strangest looping construct I've found in production code?
December 3rd, 2021

JavaScript is a fantastic server-side language because it's async. That also makes it tricky. 💩 What happens when you swallow errors? Forget to resolve promises? Or run into a number of other anti-patterns
November 3rd, 2021

TypeScript solves many of JavaScript's sharpest edges. You don't need much to get started ✌️
October 12th, 2021

A hill I will die on 👉 global CONSTANT = 'constant' are bad
September 21st, 2021

This blew my mind, thought you'd like it too. You can do more with ?. than you thought.
June 24th, 2021

Your site may be fast for users, but Google don't care. Official metrics or bust.
April 27th, 2021

Many engineers think server-side code is the scary domain of True Engineers. Something newbies, juniors, and frontend engineers shouldn't touch. They're wrong. Modern backend is a joy. ❤️
September 22nd, 2020

"He's a frontend guy, is this even a fair question to ask?" The head of engineering was worried about our systems design question …
August 7th, 2020

The Big Mac index is a purchasing power parity index published by The Economist. Jest fetch testing is a tech task so frustrating that it almost made me quit the industry. I'm writing this so you don't have to read 8234721 different blog posts, stack overflow answers, and GitHub threads with conflicting info on how to get Jest and fetch to play together.
August 22nd, 2019

I was bored Monday night and decided to see if I still know how to build with jQuery. Nothing better to do, no pressing ideas, a bit of fun. Also a favor for a friend who's preparing to talk about React to a bunch of people who've never seen it before 😛
May 24th, 2019

A fully functioning LOLCODE-to-JavaScript compiler implemented as a Babel macro. You never thought you wanted this and now here it is. You're welcome. 🐱
May 16th, 2019

February 27th, 2018

Chatroom is slow? I know, I'll just use list virtualization! List virtualization is hard, dear reader. So, how do you virtualize a list?
February 1st, 2018

January 25th, 2018

You've probably seen web notifications before. YouTube shows them when it goes to a new song, Facebook pings them when a new message comes in, scammy websites ask for permissions and you say no. The usual. You can fire those notifications from anywhere inside your JavaScript.
November 16th, 2017

There's a joke in functional programming that once you understand monads, it becomes impossible to explain them to others. The nuance is nuanced, the details are hard, let’s focus on practice
September 21st, 2017

I was doing code review for a coworker, and it soon became obvious that he used a linter and that the linter gave him a bright idea: _use strict comparisons_.
September 14th, 2017

September 4th, 2017

How many touch points does your sales process require? Do you need 2 ad clicks or 5? Two shiny demos or one fat video? As an engineer, you might not care, but this is the stuff that keeps your CEO and growth lead and head of product up at night. A business owner that can answer that 👆 question reliably is god.
May 11th, 2017

Both superagent and fetch() enable you to talk to a server. The first produces clean code that gets nesty if you need many things. The second produces clean code that is Promis-y and sometimes cumbersome. The difference between superagent and fetch() isn't that one sends your headers as-given and the other lowercases their names. The difference is that superagent sends a cookie and fetch() doesn't!
November 1st, 2016

September 26th, 2016

This is a puzzle you can run into if you’re not careful, and sometimes, despite your best efforts, even if you are careful. It happened to me when I had a settings object that I passed into a view. The view then did things. When I made a new view from the settings object, it looked like the view I had just cleared.
September 9th, 2016

July 26th, 2016

July 20th, 2016

March 11th, 2016

December 29th, 2015

Days aren't 60*60*24 seconds long. They are 1 day long, which on most days maps to 60*60*24 = 86400 seconds. But not on all days.
November 18th, 2015

November 2nd, 2015

October 16th, 2015

August 7th, 2015

June 4th, 2015

March 26th, 2015

January 27th, 2015

My favourite tool for javascript debugging is `console.log`. I mean, I love `console.log`. If I ever get a programming tattoo, it's going to be `console.log` or some variation thereof. Simple to use, works every time, and every programming language I've used since I was 9 has had some variation of it.
January 14th, 2015

November 5th, 2014

Using returns and callbacks in the same function. Sounds like crazy talk I know, but hear me out, I have good reason. I think.
June 26th, 2014

January 24th, 2014

October 15th, 2013

September 17th, 2013

July 31st, 2013

May 31st, 2013

May 3rd, 2013

March 14th, 2013

March 7th, 2013

January 10th, 2013

December 14th, 2012

November 30th, 2012

November 29th, 2012

November 19th, 2012

November 2nd, 2012

September 27th, 2012

September 20th, 2012

July 23rd, 2012

July 19th, 2012

June 1st, 2012

April 13th, 2012

April 6th, 2012

April 2nd, 2012

March 30th, 2012

March 14th, 2012

March 12th, 2012

February 24th, 2012

January 30th, 2012

January 23rd, 2012

December 23rd, 2011

December 19th, 2011

December 12th, 2011

December 7th, 2011

November 11th, 2011

October 17th, 2011

October 7th, 2011

September 16th, 2011

August 11th, 2011

May 21st, 2011

A few years ago I was playing around with JavaScript trying to find the cleanest way to implement callbacks in functions. Primarily I wanted a readable way to make certain the last argument passed is a callback, withut having to rely on knowing how many arguments there are and so on. Instead I stumbled upon a pretty cool feature of how javascript handles function arguments.
April 16th, 2011

September 22nd, 2010

July 12th, 2009

June 6th, 2009

March 25th, 2009