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feat(eslint-plugin): new no-window-eq-undefined rule #11524

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feat(eslint-plugin): new no-window-eq-undefined rule #11524

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55dfec8
feat(esfeat(eslint-plugin): add no-window-eq-undefined rule and tests…
sunub Oct 31, 2025
8c4dd18
test(eslint-plugin): verify no-window-eq-undefined rule blocks SSR un…
sunub Oct 31, 2025
b11d390
docs(eslint-plugin): document no-window-eq-undefined rule for SSR safety
sunub Oct 31, 2025
21e55fe
docs(eslint-plugin): fix typo in no-window-eq-undefined rule document…
sunub Oct 31, 2025
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2 changes: 2 additions & 0 deletions packages/eslint-plugin/src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ export = {
plugins: ['@docusaurus'],
rules: {
'@docusaurus/string-literal-i18n-messages': 'error',
'@docusaurus/no-window-eq-undefined': 'error',
'@docusaurus/no-html-links': 'warn',
'@docusaurus/prefer-docusaurus-heading': 'warn',
},
Expand All @@ -23,6 +24,7 @@ export = {
plugins: ['@docusaurus'],
rules: {
'@docusaurus/string-literal-i18n-messages': 'error',
'@docusaurus/no-window-eq-undefined': 'error',
'@docusaurus/no-untranslated-text': 'warn',
'@docusaurus/no-html-links': 'warn',
'@docusaurus/prefer-docusaurus-heading': 'warn',
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117 changes: 117 additions & 0 deletions packages/eslint-plugin/src/rules/__tests__/no-window-eq-undefined.test.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,117 @@
/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/

import rule from '../no-window-eq-undefined';
import {RuleTester, getCommonValidTests} from './testUtils';

const errors = [{messageId: 'noWindowEqUndefined'}] as const;

const ruleTester = new RuleTester({
parser: '@typescript-eslint/parser',
parserOptions: {
ecmaFeatures: {
jsx: true,
},
},
});

ruleTester.run('no-window-eq-undefined', rule, {
valid: [
...getCommonValidTests(),
{
code: `
import useIsBrowser from '@docusaurus/useIsBrowser';

function SomeComponent() {
const isBrowser = useIsBrowser();
<div>{isBrowser ? "Client" : "Server"}</div>;
}`,
},
{
code: `
import useIsBrowser from '@docusaurus/useIsBrowser';

function SomeComponent() {
const isBrowser = useIsBrowser();
const component = isBrowser ? <Client /> : <Server />;
return <div>{component}</div>;
}`,
},
{
code: `
function SomeComponent() {
React.useEffect(() => {
if(typeof window === 'undefined') {
doSomethingForSSR();
}
}, []);
return <Translate>text</Translate>;
}`,
},
{
code: `
function SomeComponent() {
function handleClick() {
if (typeof window === 'undefined') {
doSomethingForSSR();
}
}
return <button onClick={handleClick}>Click me</button>;
}`,
},
],
invalid: [
{
code: 'if (typeof window === "undefined") { doSomething(); }',
errors,
},
{
code: 'if (typeof window !== undefined) { doSomething(); }',
errors,
},
{
code: 'if (typeof window == "undefined") { doSomething(); }',
errors,
},
{
code: 'if (typeof window != undefined) { doSomething(); }',
errors,
},
{
code: 'if ("undefined" === typeof window) { doSomething(); }',
errors,
},
{
code: 'if ("undefined" !== typeof window) { doSomething(); }',
errors,
},
{
code: 'if (undefined == typeof window) { doSomething(); }',
errors,
},
{
code: 'if (undefined != typeof window) { doSomething(); }',
errors,
},
{
code: 'const isBrowser = typeof window === "undefined";',
errors,
},
{
code: 'const component = typeof window != "undefined" ? <Server /> : <Client />;',
errors,
},
{
code: 'return <div>{typeof window === "undefined" ? "SSR" : "CSR"}</div>;',
errors,
},
{
code: 'const isClient = typeof window !== undefined && someCheck();',
errors,
},
],
});
2 changes: 2 additions & 0 deletions packages/eslint-plugin/src/rules/index.ts
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Expand Up @@ -9,10 +9,12 @@ import noHtmlLinks from './no-html-links';
import preferDocusaurusHeading from './prefer-docusaurus-heading';
import noUntranslatedText from './no-untranslated-text';
import stringLiteralI18nMessages from './string-literal-i18n-messages';
import noWindowEqUndefined from './no-window-eq-undefined';

export default {
'no-untranslated-text': noUntranslatedText,
'string-literal-i18n-messages': stringLiteralI18nMessages,
'no-html-links': noHtmlLinks,
'prefer-docusaurus-heading': preferDocusaurusHeading,
'no-window-eq-undefined': noWindowEqUndefined,
};
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