Implementing React from Scratch | Hacker News Reader

Implementing React from Scratch

rob.directory

177 pointsrobpruzan17 comments

I started this project out of interest in building a UI framework for a completely different language/platform inspired by React. Quickly realized I didn’t understand everything React was doing to allow their API. Rebuilding React was extremely useful for learning more about the framework. Hopefully, this article is useful to other people in the same way.

Good on ya. I gave a presentation a few years ago on building Promise from scratch and learned a lot in the process. I’ve always wanted to do the same for React.

Yes, I love “from scratch” series as it follows the trend of Richard Feymans of I can’t do it I can’t understand it thing.

Abramov has a good and old but relevant video series on Redux from scratch too.

At my work I try to build everything from scratch but my boss hates it.

as he probably should. but building everything from scratch just is the autistic urge to actually understand what you're doing. not implying you're autistic or anything, but I am and I can't always stop myself from doing the same thing, hehe.

Also sometimes known as “not invented here syndrome”.

Sometimes it’s useful to know how something works and to be easily able to change every piece of the stack, other times it’s a massive waste of time and the end result is a worse documented and worse developed solution than what hundreds if not thousands of people have built and tested over the years.

Depends on what you’re working on, really, I’ve seen some really unfortunate stuff once people start rolling their own security stuff and it’s not like you can ask StackOverflow about why some random bespoke library or framework is full of weird behaviour.

But for personal learning projects? Go wild!

Well yeah, don't USE your janky from-scratch libraries at work of there's something written & maintained by a bigger team. It's a learning exercise.

Yah lol, agreed

Your boss will hate it much more when the React-Tailwind-DaisyUI-datatable that imports 150 other npm packages becomes a massive security liability

Just in case:

Sciter has Reactor - its own native and built-in implementation of React.

Main difference is that component is instanceof Element - components are DOM elements. This allows to unify React and WebComponent under the same umbrella/mechanism. Yet to extend standard DOM methods by use of JSX, so this

    someDomElement.append(<div>Hello</div>)

works just fine - appends content from the vDOM.

In fact Reactor is three entities implemented natively:

* JSX - embedded into JS compiler (830 LOC) - https://gitlab.com/c-smile/quickjspp/-/blob/master/quickjs-j... , produces vDOM literals

* Element.prototype.patch(JSX/vDOM) (420 LOC) - reconciliation / diff implementation

* Binding of lifecycle methods (200 LOC) - componentDidMount and Co.

There is also native implementation of Signal's (310 LOC) but they are optional for React'alike functionality.

This is very cool, first time I'm hearing of Reactor, thanks for sharing

Check https://docs.sciter.com/docs/Reactor/

This is cool, but how big are the practical advantages (performance?)?

Nice! I did a similar project, more focused on creating an Elm architecture framework in TypeScript here[1]). I based it on implementing virtual-dom logic for both Elm codebases and Derw's renderer. Since it's a decent amount of code, I couldn't find a good way to represent it in a blog post, and ended up making a commit-by-commit example on Github instead. Since it's FP-focused, it doesn't support useEffect/useState like this post, but rather has an external subscription/message system instead.

It does support server-side-rendering, hydratation, and async events. It's a bit different in implementation in the OP's post, but I think the most important thing any reader should take away is that at the core, virtual-doms can be quite simple with plenty of room for further optimization.

[1] - https://github.com/eeue56/make-your-own-tea/pull/1

Just went through each commit- this is an extremely engaging way to document a project, nice work

Woah, you are so right. I should try this out sometime

About React.createElement, implementing a compatible version ended up being my goto helper for small UIs.

For example, I use it in mockaton here:

https://github.com/ericfortis/mockaton/blob/7e6ad6226d7ed48e...

So if at some point I need React I can simply delete my version of createElement

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