Chandan Kumar ch4nd4n

(I'm enjoying doing these raw, barely edited writeups; I hope they're useful to you too)

Feature flags

This is my own writeup on feature flags; for a deep dive I'd recommend something like Martin Fowler's article (https://martinfowler.com/articles/feature-toggles.html).

So. Feature flags. The basic idea that you'll store configuration/values on a database/service somewhere, and by changing those values, you can change the user experience/features for a user on the fly.

Let's say that you're building a new feature, called 'new-button' which changes the color of buttons, which is currently red, to blue. Then you'd change code that looks like this -

(This is a draft for something I'm writing internally but figured it would be useful for everyone.)

tl;dr -

make sure git --version returns 2.27.0 or higher.
git clone --filter=blob:none --sparse <repo> --depth=1
cd <repo>
git sparse-checkout set <path> <path> <...path>

I heard some points of criticism to how React deals with reactivity and it's focus on "purity". It's interesting because there are really two approaches evolving. There's a mutable + change tracking approach and there's an immutability + referential equality testing approach. It's difficult to mix and match them when you build new features on top. So that's why React has been pushing a bit harder on immutability lately to be able to build on top of it. Both have various tradeoffs but others are doing good research in other areas, so we've decided to focus on this direction and see where it leads us.

I did want to address a few points that I didn't see get enough consideration around the tradeoffs. So here's a small brain dump.

"Compiled output results in smaller apps" - E.g. Svelte apps start smaller but the compiler output is 3-4x larger per component than the equivalent VDOM approach. This is mostly due to the code that is usually shared in the VDOM "VM" needs to be inlined into each component. The tr

In production, it is recommended to minify any JavaScript code that is included with your application. Minification can help your website load several times faster, especially as the size of your JavaScript source code grows.

Here's one way to set it up:

Install Node.js
Run npm init -y in your project folder (don't skip this step!)
Run npm install terser

Now, to minify a file called like_button.js, run in the terminal:

The One Secret Trick To Becoming A Genius Programmer

Okay, the title of this post is a bit of a lie. There's no one secret trick to becoming a genius programmer - there are two, and they're more habits than tricks. Nevertheless, these kind of 'secret tricks' seem to resonate with people, so I went for this title anyway.

Every once in a while, a somewhat strange thing happens to me. I'll be helping somebody out on IRC - usually a beginner - answering a number of their questions in rapid succession, about a variety of topics. Then after a while, they call me a "genius" for being able to answer everything they're asking; either directly, or while talking about me to somebody else.

Now, I don't really agree with this "genius" characterization, and it can make me feel a bit awkward, but it shows that a lot of developers have a somewhat idealistic and nebulous notion of the "genius programmer" - the programmer that knows everything, who can do everything, who's never stumped by a problem, and of which ther

Don't use VPN services.

No, seriously, don't. You're probably reading this because you've asked what VPN service to use, and this is the answer.

Note: The content in this post does not apply to using VPN for their intended purpose; that is, as a virtual private (internal) network. It only applies to using it as a glorified proxy, which is what every third-party "VPN provider" does.

A Russian translation of this article can be found here, contributed by Timur Demin.
A Turkish translation can be found here, contributed by agyild.
There's also this article about VPN services, which is honestly better written (and has more cat pictures!) than my article.

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

	function CopyButton({ value }) {
	let [copied, setCopied] = React.useState();
	let hydrated = usePageIsHydrated();
	React.useEffect(() => {
	let id = setTimeout(() => setCopied(false), 2000);
	return () => clearTimeout(id);
	}, [copied]);

	return (
	<button

	# Plain Ol' Node
	node --max-old-space-size=1024 app.js # increase to 1gb
	node --max-old-space-size=2048 app.js # increase to 2gb
	node --max-old-space-size=3072 app.js # increase to 3gb
	node --max-old-space-size=4096 app.js # increase to 4gb
	node --max-old-space-size=5120 app.js # increase to 5gb
	node --max-old-space-size=6144 app.js # increase to 6gb

	# For pm2
	pm2 start app.js --node-args="--max-old-space-size=1024" # increase to 1gb

	--log_gc (Log heap samples on garbage collection for the hp2ps tool.)
	type: bool default: false
	--expose_gc (expose gc extension)
	type: bool default: false
	--max_new_space_size (max size of the new generation (in kBytes))
	type: int default: 0
	--max_old_space_size (max size of the old generation (in Mbytes))
	type: int default: 0
	--max_executable_size (max size of executable memory (in Mbytes))
	type: int default: 0