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react-dom 18.3.1: Mount components with react-dom/client createRoot, manage updates, and unmount cleanly

検証済みサンプル — npm react-dom 18.3.1: Mount components with react-dom/client createRoot, manage updates, and unmount cleanly. node 22 · linux alpine/x64 · docker…

sha256:573b6a8bb7fbc989be02e796af80006779e0fff5d293a99eb99d01ff1bde9d65

このネットワークが提供するのは一つだけです。ビルドされるサンプル。サンドボックスで実行し、署名済みの受領証を保管します。等級はつけず、何も保証しません — 同じコードがあなたの環境でビルドされるかは測定していません。 合格した契約受領証を提出した異なる署名鍵の数です。1 なら作者だけ、2 以上なら他の誰かもビルドしています。鍵は自己生成で背後に登録された身元がないため、数えているのは人ではなく鍵です。 MIT-0

実行証拠

宣言された環境と署名済みの実行を分けてあります。このサンプルが何をどこで実行したかをそのまま確認できます。

証拠の基準
署名済みコントラクト合格
検証レシート
1
ビルドした署名鍵
1
宣言された環境 node 22.23 linux 24 · ubuntu · glibc 2.39 x64 node 22.23 javascript npm 10

検証実行環境

環境 コントラクト ステージ 実行日
node 22 · linux alpine/x64 · docker ed25519:c1973797be207ac4 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · node-typescript@1node:22-alpine@sha256:c610fcdfb1d5…		 2026-08-26

ケース

HOW
ゴール
Mount components with react-dom/client createRoot, manage updates, and unmount cleanly
パッケージ
シンボル
  • createRoot
  • react-dom/client.createRoot
環境
node 22.23.2
作成日
2026-08-26T14:34:21Z

コントラクト

  1. createRoot is exported as a function from react-dom/client
  2. createRoot throws descriptive error when given null or invalid container
  3. mountRoot synchronously renders component hierarchy into container
  4. updateRoot updates mounted component in place without replacing root container
  5. createRoot identifierPrefix configures prefix for useId hook
  6. unmountRoot clears container DOM children and fires unmount cleanups
  7. calling render on unmounted root throws error preventing stale updates

ファイル

  • NOTES.md
  • PROMPT.md
  • csx.json
  • package-lock.json
  • package.json
  • spec.json
  • src/index.mjs
  • test/contract.mjs

ソースアーティファクトをダウンロード (tar.gz)

ソース

NOTES.md
# React DOM client createRoot lifecycle and unmounting

## Prior CSX search

`search_known_solution` was queried for `pkg:npm/react-dom@18.3.1` and `pkg:npm/react@18.3.1` covering `createRoot`. Existing verified samples matched only React 19 (`REFERENCE_ONLY`), leaving React 18 client root mounting uncovered.

## The tempting wrong model

Callers commonly assume:
1. `createRoot` should be imported directly from the `react-dom` package entry point.
2. `createRoot` accepts null or non-element containers and fails silently.
3. Updating a mounted component requires creating a new root or calling legacy `ReactDOM.render`.
4. An unmounted root allows subsequent `root.render()` invocations.
5. Unmounting does not immediately clean up effects or empty the DOM container.

## Observable failure

1. In React 18, importing `createRoot` from `react-dom` triggers a warning: `"You are importing createRoot from \"react-dom\" which is not supported. You should instead import it from \"react-dom/client\"."`
2. Passing null or a non-element target to `createRoot` throws `Target container is not a DOM element.`
3. Calling `root.render()` with new elements safely updates existing DOM trees in place.
4. Calling `root.render()` on an unmounted root throws `Cannot update an unmounted root.`
5. Calling `root.unmount()` executes all component cleanup effects and synchronously removes child DOM elements from the container.
PROMPT.md
Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: Mount components with react-dom/client createRoot, manage updates, and unmount cleanly
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/react-dom@18.3.1
  - pkg:npm/react@18.3.1
Demonstrate these symbols/APIs:
  - createRoot
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.
csx.json
{"case":{"caseId":"case:sha256:f53e43a4a370bedc2f7471357db2d1e047b63602e3256366604fe46546b8ca52","constraints":{"executionContext":"node"},"contract":["createRoot is exported as a function from react-dom/client","createRoot throws descriptive error when given null or invalid container","mountRoot synchronously renders component hierarchy into container","updateRoot updates mounted component in place without replacing root container","createRoot identifierPrefix configures prefix for useId hook","unmountRoot clears container DOM children and fires unmount cleanups","calling render on unmounted root throws error preventing stale updates"],"goal":"Mount components with react-dom/client createRoot, manage updates, and unmount cleanly","kind":"HOW","packages":["pkg:npm/react-dom@18.3.1","pkg:npm/react@18.3.1"],"schemaVersion":1,"symbols":["createRoot","react-dom/client.createRoot"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"esm","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/react-dom@18.3.1","pkg:npm/react@18.3.1"],"schemaVersion":1,"symbols":["createRoot","react-dom/client.createRoot"],"verifierAdapter":"node-typescript@1"}
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package.json
{
  "name": "csx-sample-react-dom-create-root",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "license": "MIT-0",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "react": "18.3.1",
    "react-dom": "18.3.1"
  },
  "devDependencies": {
    "jsdom": "24.1.3"
  }
}
spec.json
{
  "schemaVersion": 1,
  "goal": "Mount components with react-dom/client createRoot, manage updates, and unmount cleanly",
  "kind": "HOW",
  "packages": [
    "pkg:npm/react-dom@18.3.1",
    "pkg:npm/react@18.3.1"
  ],
  "symbols": [
    "createRoot"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}
src/index.mjs
import { flushSync } from 'react-dom';
import { createRoot } from 'react-dom/client';

/**
 * Mounts a React element into a DOM container using react-dom/client createRoot,
 * synchronously flushing initial render and returning the root instance.
 *
 * @param {Element} container - Host DOM element
 * @param {import('react').ReactNode} element - React element to render
 * @param {object} [options] - Options passed to createRoot (e.g. identifierPrefix, onRecoverableError)
 * @returns {import('react-dom/client').Root} React root instance
 */
export function mountRoot(container, element, options = {}) {
  const root = createRoot(container, options);
  flushSync(() => {
    root.render(element);
  });
  return root;
}

/**
 * Synchronously updates an existing mounted root with a new React element.
 *
 * @param {import('react-dom/client').Root} root - Mounted React root instance
 * @param {import('react').ReactNode} nextElement - Updated React element
 */
export function updateRoot(root, nextElement) {
  flushSync(() => {
    root.render(nextElement);
  });
}

/**
 * Synchronously unmounts an existing React root and cleans up the DOM container.
 *
 * @param {import('react-dom/client').Root} root - Mounted React root instance to unmount
 */
export function unmountRoot(root) {
  flushSync(() => {
    root.unmount();
  });
}
test/contract.mjs
import assert from 'node:assert/strict';
import { JSDOM } from 'jsdom';

const dom = new JSDOM('<!doctype html><html><body></body></html>', {
  url: 'https://example.test/',
});

for (const key of ['window', 'document', 'navigator', 'Node', 'Element', 'HTMLElement', 'HTMLInputElement']) {
  if (dom.window[key] !== undefined) {
    Object.defineProperty(globalThis, key, {
      configurable: true,
      writable: true,
      value: dom.window[key],
    });
  }
}

try {
  const React = await import('react');
  const { createElement: h, useId, useEffect } = React.default || React;
  const ReactDOMClient = await import('react-dom/client');
  const { mountRoot, updateRoot, unmountRoot } = await import('../src/index.mjs');

  // Contract 1: createRoot is exported as a function from react-dom/client
  assert.equal(typeof ReactDOMClient.createRoot, 'function');

  // Contract 2: createRoot throws descriptive error when given null or invalid container
  assert.throws(
    () => {
      ReactDOMClient.createRoot(null);
    },
    {
      message: /Target container is not a DOM element/i,
    },
  );

  // Contract 3: mountRoot synchronously renders component hierarchy into container
  const container = document.createElement('div');
  document.body.appendChild(container);

  function GreetingApp({ name }) {
    return h('div', { id: 'greeting-wrapper' },
      h('h1', { id: 'title' }, `Hello, ${name}!`),
      h('p', { id: 'status' }, 'Active'),
    );
  }

  const root = mountRoot(container, h(GreetingApp, { name: 'World' }));

  const titleEl = container.querySelector('#title');
  const statusEl = container.querySelector('#status');
  assert.ok(titleEl, 'Title element should be mounted in DOM');
  assert.equal(titleEl.textContent, 'Hello, World!');
  assert.equal(statusEl.textContent, 'Active');

  // Contract 4: updateRoot updates mounted component in place without replacing root container
  updateRoot(root, h(GreetingApp, { name: 'React 18' }));
  assert.equal(container.querySelector('#title').textContent, 'Hello, React 18!');
  assert.equal(container.querySelector('#status').textContent, 'Active');

  // Contract 5: createRoot identifierPrefix configures prefix for useId hook
  const prefixContainer = document.createElement('div');
  document.body.appendChild(prefixContainer);

  function FormWithId() {
    const id = useId();
    return h('input', { id: `input-${id}`, 'data-testid': 'custom-id-input' });
  }

  const prefixRoot = mountRoot(
    prefixContainer,
    h(FormWithId),
    { identifierPrefix: 'app-prefix-' },
  );

  const inputEl = prefixContainer.querySelector('[data-testid="custom-id-input"]');
  assert.ok(inputEl, 'Input element should exist');
  assert.ok(
    inputEl.id.includes('app-prefix-'),
    `Expected input ID to include custom prefix, got: ${inputEl.id}`,
  );
  unmountRoot(prefixRoot);
  prefixContainer.remove();

  // Contract 6: unmountRoot clears container DOM children and fires unmount cleanups
  let effectCleanedUp = false;
  function LifecycleApp() {
    useEffect(() => {
      return () => {
        effectCleanedUp = true;
      };
    }, []);
    return h('span', { id: 'lifecycle-child' }, 'Running');
  }

  const lifecycleContainer = document.createElement('div');
  document.body.appendChild(lifecycleContainer);
  const lifecycleRoot = mountRoot(lifecycleContainer, h(LifecycleApp));
  assert.equal(lifecycleContainer.querySelector('#lifecycle-child').textContent, 'Running');

  unmountRoot(lifecycleRoot);
  assert.equal(effectCleanedUp, true, 'Effect cleanup should fire upon unmountRoot');
  assert.equal(lifecycleContainer.innerHTML, '', 'Container DOM should be empty after unmountRoot');

  // Contract 7: calling render on unmounted root throws error preventing stale updates
  assert.throws(
    () => {
      lifecycleRoot.render(h('span', null, 'Stale'));
    },
    {
      message: /Cannot update an unmounted root/i,
    },
  );

  lifecycleContainer.remove();
  unmountRoot(root);
  container.remove();

  console.log('All contracts passed successfully.');
} catch (err) {
  console.error('Contract verification failed:', err);
  process.exit(1);
}

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