Advanced / Owner & Introspection

createRoot

Creates a reactive root — an owner scope with its own dispose(). A root created inside an existing owner is owned by it and is disposed when the parent is disposed; call dispose() to tear it down earlier. To create a root that outlives its creator, detach explicitly: runWithOwner(null, () => createRoot(...)). Pass id to seed hydration ids for the tree it owns.

const dispose = createRoot((dispose) => {
  // ...
  return dispose;
});

// Detached from the current owner (lives until `detached()` is called):
const detached = runWithOwner(null, () => createRoot((d) => d));

Hydration: a root created during hydration marks itself as the snapshot scope, so writes landing during the hydration pass are held until the pass completes (the mark used to depend on which primitive ran first under it).

render() creates the root for normal app code. Reach for createRoot in tests, libraries, or non-render entry points that need to host a reactive scope.

Import

import { createRoot } from "solid-js";

Type signature

function createRoot<T>(
  init: ((dispose: () => void) => T) | (() => T),
  options?: { id?: string; transparent?: boolean }
): T;

Parameters

`init`

Type: ((dispose: () => void) => T) | (() => T)

`options`

Type: { id?: string; transparent?: boolean }
Optional

Examples

// At module level there is no owner, so this root lives until disposed.
const dispose = createRoot((dispose) => {
  const [n, setN] = createSignal(0);
  createEffect(
    () => n(),
    (value) => console.log(value)
  );
  setInterval(() => setN((x) => x + 1), 1000);
  return dispose;
});

// Later, to tear everything down:
dispose();

// Inside an owner (component, effect, another root), detach explicitly
// if the root must outlive its creator:
const detached = runWithOwner(null, () => createRoot((d) => d));

Learn more

Last updated: 9/27/26, 8:14 AMEdit this pageReport an issue with this page