allow globals by default

Author: mmkal

docs/rules/isolated-functions.md

@@ -14,6 +14,8 @@ Common scenarios where functions must be isolated:
 - Server actions or other remote execution contexts
 - Functions with specific JSDoc annotations
 
+By default, this rule allows global variables (like `console`, `fetch`, etc.) in isolated functions, but prevents usage of variables from the surrounding scope.
+
 ## Fail
 
 ```js
@@ -80,6 +82,19 @@ function abc() {
 }
 ```
 
+```js
+import makeSynchronous from 'make-synchronous';
+
+export const fetchSync = () => {
+	const getText = makeSynchronous(async () => {
+		console.log('Starting...'); // ✅ Global variables are allowed by default
+		const res = await fetch('https://example.com'); // ✅ Global variables are allowed by default
+		return res.text();
+	});
+	console.log(getText());
+};
+```
+
 ## Options
 
 Type: `object`
@@ -130,12 +145,12 @@ Array of comment strings that mark functions as isolated. Functions with JSDoc c
 ### globals
 
 Type: `boolean | string[]`\
-Default: `false`
+Default: `true`
 
 Controls how global variables are handled:
 
-- `false` (default): Global variables are not allowed in isolated functions
-- `true`: All globals from ESLint's language options are allowed
+- `false`: Global variables are not allowed in isolated functions
+- `true` (default): All globals from ESLint's language options are allowed
 - `string[]`: Only the specified global variable names are allowed
 
 ```js

rules/isolated-functions.js

@@ -1,4 +1,3 @@
-'use strict';
 import esquery from 'esquery';
 import functionTypes from './ast/function-types.js';
 
@@ -16,26 +15,31 @@ const parseEsquerySelector = selector => {
 	return parsedEsquerySelectors.get(selector);
 };
 
+/** @type {{functions: string[], selectors: string[], comments: string[], globals: boolean | string[]}} */
+const defaultOptions = {
+	functions: ['makeSynchronous'],
+	selectors: [],
+	comments: ['@isolated'],
+	globals: true,
+};
+
 /** @param {import('eslint').Rule.RuleContext} context */
 const create = context => {
 	const {sourceCode} = context;
-	/** @type {{functions: string[], selectors: string[], comments: string[], globals: boolean | string[]}} */
-	const userOptions = context.options[0];
-	/** @type {typeof userOptions} */
+	/** @type {typeof defaultOptions} */
 	const options = {
-		functions: ['makeSynchronous'],
-		selectors: [],
-		comments: ['@isolated'],
-		globals: false,
-		...userOptions,
+		...defaultOptions,
+		...context.options[0],
 	};
 
 	options.comments = options.comments.map(comment => comment.toLowerCase());
-	const allowedGlobals = options.globals === true
-		? Object.keys(context.languageOptions.globals)
-		: (Array.isArray(options.globals)
-			? options.globals
-			: []);
+	/** @type {string[]} */
+	let allowedGlobals = [];
+	if (options.globals === true) {
+		allowedGlobals = Object.keys(context.languageOptions.globals);
+	} else if (Array.isArray(options.globals)) {
+		allowedGlobals = options.globals;
+	}
 
 	/** @param {import('estree').Node} node */
 	const checkForExternallyScopedVariables = node => {
@@ -155,6 +159,7 @@ export default {
 			recommended: true,
 		},
 		schema,
+		defaultOptions: [defaultOptions],
 		messages,
 	},
 };

test/isolated-functions.js

@@ -94,16 +94,6 @@ test({
 			`),
 			errors: [error({name: 'foo', reason: 'follows comment containing "@isolated"'})],
 		},
-		{
-			name: 'global variables not allowed by default',
-			languageOptions: {globals: {foo: true}},
-			code: stripIndent(`
-				makeSynchronous(function () {
-					return foo.slice();
-				});
-			`),
-			errors: [fooInMakeSynchronousError],
-		},
 		{
 			name: 'global variables can be explicitly disallowed',
 			languageOptions: {globals: {foo: true}},
@@ -179,7 +169,16 @@ test({
 			`),
 		},
 		{
-			name: 'can allow global variables from language options',
+			name: 'can implicitly allow global variables from language options',
+			languageOptions: {globals: {foo: true}},
+			code: stripIndent(`
+				makeSynchronous(function () {
+					return foo.slice();
+				});
+			`),
+		},
+		{
+			name: 'can explicitly allow global variables from language options',
 			languageOptions: {globals: {foo: true}},
 			options: [{globals: true}],
 			code: stripIndent(`