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Oliver Jumpertz Profile picture
@oliverjumpertz
Jul 12, 2021 • 40 tweets • 10 min read • Read on X
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I've created many more visual tips and explanations since I posted my last collection in June.

This is a new collection of visual tips and explanations for JavaScript that can help web developers of any skill level with even more content!

A thread.
1. The Anatomy Of A For-Loop In JavaScript .
2. The Anatomy Of A Do-While-Loop In JavaScript .
3. The Anatomy Of A While-Loop In JavaScript .
4. Anatomy Of A For..Of Loop In JavaScript .
5. The Anatomy Of Array.map in JavaScript .
6. The Anatomy Of An Object Destructuring Assignment .
7. How To Create A Cancelable Promise Delay .
8. How To Make An Argument Required With Default Parameters .
9. The Performance API .
10. How To Infinitely Flatten An Array .
11. The Nullish Coalescing Operator .
12. Object Destructuring Assignments .
13. Destructuring An Object Into Existing Variables .
14. Array Destructuring .
15. Getting The Last Items Of An Array .
16. Formatting The Output Of JSON.stringify .
17. How To Prevent An Optional Object Key From Being Always Enumerable .
18. How To Destructure From A Possibly Undefined Property .
19. Pushing To Arrays In An Immutable Way .
20. Swapping Two Variables With Array Destructuring .
21. How To Swap To Elements Of An Array In-Place With Array Destructuring .
22. Creating A Python-Like Range Functions .
23. Creating A Lazy Range Function .
24. A Memoized Fibonacci Function .
25. How To Connect To MetaMask With ethers.js .
26. Getting All Unique Values From An Array .
27. How To Sum Up Array Values With Reduce .
28. Short-Circuit Evaluation With The Logical OR .
29. Short-Circuit Evaluation With The Logical AND .
30. JavaScript's Automatic Semicolon Insertion .
31. Make Your Numbers More Readable With Numeric Separators .
32. How To Quickly Filter Out All Falsy Values From An Array .
33. Making Objects Immutable With Freeze .
34. Making Arrays Immutable With Freeze .
35. Spreading Sparse Arrays To Leave Out Optional Arguments .
36. Destructuring Function Parameters To Increase Usability .
37. Abstract vs. Strict Equality Comparison .
38. The Match Statement Proposal .
39. Thread End

That's it for this collection of 38 visual tips and explanations about JavaScript.

I hope you found something useful! 💛

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More from @oliverjumpertz

Oliver Jumpertz Profile picture
Sep 20, 2023
If you're using AWS Lambda, stop scrolling and find out how you can potentially save a few to a few thousand dollars a month.

I actually saved my employer 8k dollars a month from only two Lambda@Edge functions running for each CloudFront request:
Did you know that whenever you deploy a Lamda function to AWS, it automatically tries to create a log group for you and automatically starts to send even only access logs through that pipe?
Even if you don't have a single log statement within your Lambda function, the Lambda runtime will write access logs to CloudWatch.

AWS will happily bill you for that without you probably noticing, especially if you don't intentionally log anything.
Read 8 tweets
Oliver Jumpertz Profile picture
Feb 21, 2023
Git is by far the most used source control management tool out there.

It is basially an essential to know. And this justifies knowing a few of the most important git commands you need in your daily work.

Here are 19 that any developer should know: 19 essential git commands for every developer.
1. Initialize a repository

git init is the most basic command.

It initializes a new repository in your current folder and starts the version control flow for your repository. git init
2. Clone a remote repository

You don't necessarily need to create a new repository.

Sometimes you just want to download an existing repository and contribute to it.

This is where git clone comes in. git clone <remoteUrl/>
Read 21 tweets
Oliver Jumpertz Profile picture
Feb 20, 2023
I've seen some people complaining about Twitter putting text-based 2FA behind the paywall.

There is gladly a far better way that still works for everyone (and to be honest, text-based 2FA is flawed).

A small tutorial:
Go to "Settings and Support". .
Now lick on "Settings and privacy". .
Read 13 tweets
Oliver Jumpertz Profile picture
Feb 9, 2023
If you learn Rust, you'll learn much more about computers and optimization/programming than many other programming languages can even teach you.

Want an example?

The Rust compiler can optimize away the discriminant of an enum by using invalid bit patterns for fields. ↓
Consider this scenario:

enum GlassState {
Filled(u8, bool)
Empty
}

And let's now simplify how that "looks" in memory:

Filled(69, true) => [69, 1]
Filled(69, false) => [69, 0]

And what about Empty?

Well... -> Empty => [0, 2]
What happened here?

The first value is irrelevant.

An Empty does not have the same u8 as the variant Filled has.

You can put anything in the first place; it will never get read but still takes up space.

The second value, however, is an invalid bit pattern for a boolean.
Read 5 tweets
Oliver Jumpertz Profile picture
Jan 23, 2023
The hardest part of being a senior software engineer:

Having experience.

Sometimes, experience tells us to take care of a million things that might not even be relevant to the case at hand.

Sometimes, experience hinders you from iterating fast.
It may sound counterintuitive, but it can really be a problem.

"What if this happens?"

"We once had this case where X happened; we need to guard against that!"

"We should probably add X and Y, so we don't run into Z..."
Often, objections like these are valid, but also, often, they are not because you want to gather data to see what's really relevant.

A prototype does not need an extended set of safety guarantees if deployed in a completely new scenario.
Read 6 tweets
Oliver Jumpertz Profile picture
Jan 20, 2023
Algorithms in Rust:

This is the infamous fast inverse square root implemented in Rust.

This particular implementation was initially discovered in Quake III Arena's source code and rose to fame in 2002 and 2003.

Oh, and it shows some pretty interesting traits: const THREE_HALFS: f32 = 1.5; const WTF: u32 = 0x5f3759df;
As the graphic already states, the inverse square root is often used in computer graphics.

It is used to calculate reflections of lighting and shading, when normalizing corresponding vectors.
In 1998 and 1999, computing power was far away from the levels we have today, and this often required some clever use of maths or algorithmics to make things fast enough, especially in games and graphics.
Read 10 tweets

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