Implementing React from Scratch

https://www.rob.directory/blog/react-from-scratch

by robpruzan • 2 years ago

177 17 2 years ago

robpruzan3• 2 years ago

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.

jinushaun• 2 years ago

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.

siamese_puff2• 2 years ago

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.

amelius• 2 years ago

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

efortis• 2 years ago

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

c-smile2• 2 years ago

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.

robpruzan3• 2 years ago

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

c-smile2• 2 years ago

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

solarkraft• 2 years ago

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

eeue56• 2 years ago

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

robpruzan3• 2 years ago

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

LoganDark2• 2 years ago

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

Implementing React from Scratch

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