A single-file <1kb min+gzip simplified implementation of the reactive core of Solid, optimized for clean code.

Check out the annotated source, if you'd like to more in depth understand how Solid works, or if you'd like to write something similar yourself, this should be a good starting point for you.

Compared to how Solid's reactivity system actually works there are the following (known) differences:

• "Only" these functions are implemented: createSignal, createEffect, createMemo, createRoot, createContext, useContext, getOwner, runWithOwner, onCleanup, onError, batch and untrack.
• createSignal's setter doesn't give you the current updated value inside a batch, but instead gives you the same value that the getter would give you.
• createEffect doesn't schedule effects, they are executed immediately just like memos. In Solid they are scheduled if they exist inside a root.
• createEffect and createMemo don't pass the previous execution's return value to your function, just put the value in a variable outside of the function yourself to remember it, if you need that.
• createContext gives you get/set functions instead of a Provider component, as the Provider component only really makes sense in a UI context and Solid doesn't expose a lower-level context primitive.
• createContext's set function will register the context value with the parent observer, so you need to create a custom parent observer yourself (which is basically what Provider does), if you need that.
• Flimsy uses a MobX-like propagation algorithm, where computations in the reactive graph are marked stale/ready, Solid should work similarly, but I don't understand it well enough to know what the differences may be.
• Flimsy doesn't care about performance nor memory usage, it instead optimizes for clean code.
• Flimsy is probably buggier, hence the name, though if you report a bug I'll look into it.
• Solid's reactivity system doesn't do anything on the server by default, you'll have to explicitly use the browser build to make it work, Flimsy is isomorphic.

npm install --save flimsy

You should be able to use these functions pretty much just like you would use Solid's, for example:

import {createSignal, createEffect, createMemo} from 'flimsy';

// Make a counter, a memo from the counter, and log both in an effect

const [count, setCount] = createSignal ( 0 );

const double = createMemo ( () => count () * 2 );

createEffect ( () => {

  console.log ( 'count', count () );
  console.log ( 'double', double () );

});

MIT © Fabio Spampinato