solidjs-reactivity

name	solidjs-reactivity
description	Implements SolidJS reactive patterns using signals, effects, and memos. Use when writing or reviewing SolidJS components, state management, or reactive code. Covers the core mental model: components run once, signals track in reactive scopes, and props must not be destructured.

SolidJS Reactivity

Core Mental Model

SolidJS is NOT React. The fundamental differences:

1. Components run once — A component function executes a single time to set up the reactive graph. It never re-runs.
2. Reactivity is automatic — Signal reads inside tracking scopes create subscriptions. No dependency arrays.
3. Fine-grained updates — Only the specific DOM nodes or computations that depend on a signal update when it changes. No virtual DOM diffing.

// The component function runs ONCE. Only the {count()} expression re-evaluates.
function Counter() {
  const [count, setCount] = createSignal(0);
  console.log("This logs once, not on every update");
  return <button onClick={() => setCount(c => c + 1)}>{count()}</button>;
}

createSignal

Creates a reactive value with a getter (accessor) and setter.

 { createSignal }  ;

 [count, setCount] = ();


(); 


();
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