fix(react): guard ThemeProvider default context against undefined document#2478
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…ument The `context = document?.body` default in ThemeProvider threw `ReferenceError: document is not defined` under SSR (e.g. Next.js App Router prerendering a client component). Optional chaining only guards null/undefined values, not an undeclared global, so reading `document` itself throws first. Use `typeof document !== 'undefined'` to fall back to `undefined` on the server; the component's existing `context?.` guards already handle a missing context. Browser behavior is unchanged. Introduced in #1328, which intended to make ThemeProvider SSR-safe but used optional chaining that never actually protected against the undeclared global. - Add a node-environment regression test (theme.ssr.test.tsx) that renders ThemeProvider via renderToString with no document present. - Guard the DOM shims in setupTests.ts so shared setup runs under the node test environment too.
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Pull request overview
Fixes an SSR crash in the React ThemeProvider default context parameter by avoiding direct evaluation of the document global when it may be undeclared (e.g., Node/SSR runtimes), and adds regression coverage for that scenario.
Changes:
- Updated
ThemeProvider’s defaultcontextto use atypeof document !== 'undefined'guard to preventReferenceErrorunder SSR. - Guarded DOM-dependent clipboard/
execCommandshims in the shared Jest setup so it can run under a Node test environment. - Added a Node-environment SSR test ensuring
renderToString(<ThemeProvider />)does not throw whendocumentis undefined.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| packages/react/src/setupTests.ts | Adds typeof guards so DOM shims don’t execute when navigator/document are absent (node env). |
| packages/react/src/contexts/theme.tsx | Makes the context default SSR-safe by guarding access to document.body. |
| packages/react/src/contexts/theme.ssr.test.tsx | Introduces a node-environment regression test covering the SSR crash scenario. |
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chornonoh-vova
previously approved these changes
Jul 16, 2026
rheisler-deque
previously approved these changes
Jul 20, 2026
rheisler-deque
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This PR looks great, nice job testing to make sure the fix works and to protect against regression!
frankensteinke
dismissed stale reviews from rheisler-deque and chornonoh-vova
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July 20, 2026 19:50
f1ea880
rheisler-deque
approved these changes
Jul 21, 2026
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Summary
ThemeProvider's default parametercontext = document?.bodythrowsReferenceError: document is not definedunder any SSR runtime (e.g. Next.js App Router prerendering a"use client"component). Optional chaining only guards against null/undefined values — it does not protect against an undeclared global, so evaluating thedocumentidentifier itself throws before?.ever runs.This makes
<ThemeProvider>(without an explicitcontextprop) unusable in any SSR framework. Passingcontext={null}works around it, confirming the default param is the cause.Root cause / history
Introduced on 2024-01-31 in #1328 — a PR that intended to make
ThemeProviderSSR-safe (document.body→document?.body) but used optional chaining, which never actually protected against the undeclared global. This is a pre-existing bug ondevelop, independent of module format (reproduces on CJS today).Fix
typeofis safe on undeclared globals. In the browser, behavior is identical (document.body); under SSR,contextisundefined, and the component's existingcontext?.guards (effects + MutationObserver) already bail out on a falsy context.Tests
theme.ssr.test.tsxruns under@jest-environment node, wheredocumentgenuinely doesn't exist, and assertsrenderToString(<ThemeProvider …>)doesn't throw. Verified red without the fix (exactReferenceErrorattheme.tsx:32) → green with it. A separate node-env file is used rather than deletingglobal.documentin the jsdom suite, which destabilizes jsdom's async teardown.navigator.clipboard/document.execCommandshims withtypeof … !== 'undefined'so the shared setup also runs under the node environment.Verification
execCommand-dependent suites (CopyButton, Code) plus TreeView still pass — the setup guard preserves jsdom behavior.