eslint-plugin-unicorn/rules/prefer-global-this.js

More than 100 powerful ESLint rules

const MESSAGE_ID_ERROR = 'prefer-global-this/error';
const messages = {
	[MESSAGE_ID_ERROR]: 'Prefer `{{replacement}}` over `{{value}}`.',
};

const globalIdentifier = new Set([
	'window',
	'self',
	'global',
]);

const windowSpecificEvents = new Set([
	'resize',
	'blur',
	'focus',
	'load',
	'scroll',
	'scrollend',
	'wheel',
	'beforeunload', // Browsers might have specific behaviors on exactly `window.onbeforeunload =`
	'message',
	'messageerror',
	'pagehide',
	'pagereveal',
	'pageshow',
	'pageswap',
	'unload',
]);

/**
Note: What kind of API should be a windows-specific interface?

1. It's directly related to window (✅ window.close())
2. It does NOT work well as globalThis.x or x (✅ window.frames, window.top)

Some constructors are occasionally related to window (like Element !== iframe.contentWindow.Element), but they don't need to mention window anyway.

Please use these criteria to decide whether an API should be added here. Context: https://github.com/sindresorhus/eslint-plugin-unicorn/pull/2410#discussion_r1695312427
*/
const windowSpecificAPIs = new Set([
	// Properties and methods
	// https://html.spec.whatwg.org/multipage/nav-history-apis.html#the-window-object
	'name',
	'locationbar',
	'menubar',
	'personalbar',
	'scrollbars',
	'statusbar',
	'toolbar',
	'status',
	'close',
	'closed',
	'stop',
	'focus',
	'blur',
	'frames',
	'length',
	'top',
	'opener',
	'parent',
	'frameElement',
	'open',
	'originAgentCluster',
	'postMessage',

	// Events commonly associated with "window"
	...[...windowSpecificEvents].map(event => `on${event}`),

	// To add/remove/dispatch events that are commonly associated with "window"
	// https://www.w3.org/TR/DOM-Level-2-Events/events.html#Events-flow
	'addEventListener',
	'removeEventListener',
	'dispatchEvent',

	// https://dom.spec.whatwg.org/#idl-index
	'event', // Deprecated and quirky, best left untouched

	// https://drafts.csswg.org/cssom-view/#idl-index
	'screen',
	'visualViewport',
	'moveTo',
	'moveBy',
	'resizeTo',
	'resizeBy',
	'innerWidth',
	'innerHeight',
	'outerWidth',
	'outerHeight',
	'scrollX',
	'pageXOffset',
	'scrollY',
	'pageYOffset',
	'scroll',
	'scrollTo',
	'scrollBy',
	'screenX',
	'screenLeft',
	'screenY',
	'screenTop',
	'screenWidth',
	'screenHeight',
	'devicePixelRatio',
]);

const webWorkerSpecificAPIs = new Set([
	// https://html.spec.whatwg.org/multipage/workers.html#the-workerglobalscope-common-interface
	'addEventListener',
	'removeEventListener',
	'dispatchEvent',

	'self',
	'location',
	'navigator',
	'onerror',
	'onlanguagechange',
	'onoffline',
	'ononline',
	'onrejectionhandled',
	'onunhandledrejection',

	// https://html.spec.whatwg.org/multipage/workers.html#dedicated-workers-and-the-dedicatedworkerglobalscope-interface
	'name',
	'postMessage',
	'onconnect',
]);

/**
Check if the node is a window-specific API.

@param {import('estree').MemberExpression} node
@returns {boolean}
*/
const isWindowSpecificAPI = node => {
	if (node.type !== 'MemberExpression') {
		return false;
	}

	if (node.object.name !== 'window' || node.property.type !== 'Identifier') {
		return false;
	}

	if (windowSpecificAPIs.has(node.property.name)) {
		if (['addEventListener', 'removeEventListener', 'dispatchEvent'].includes(node.property.name) && node.parent.type === 'CallExpression' && node.parent.callee === node) {
			const argument = node.parent.arguments[0];
			return argument && argument.type === 'Literal' && windowSpecificEvents.has(argument.value);
		}

		return true;
	}

	return false;
};

/**
@param {import('estree').Identifier} identifier
@returns {boolean}
*/
function isComputedMemberExpressionObject(identifier) {
	return identifier.parent.type === 'MemberExpression' && identifier.parent.computed && identifier.parent.object === identifier;
}

/**
Check if the node is a web worker specific API.

@param {import('estree').MemberExpression} node
@returns {boolean}
*/
const isWebWorkerSpecificAPI = node => node.type === 'MemberExpression' && node.object.name === 'self' && node.property.type === 'Identifier' && webWorkerSpecificAPIs.has(node.property.name);

/** @param {import('eslint').Rule.RuleContext} context */
const create = context => ({
	* Program(program) {
		const scope = context.sourceCode.getScope(program);

		const references = [
			// Variables declared at globals options
			...scope.variables.flatMap(variable => globalIdentifier.has(variable.name) ? variable.references : []),
			// Variables not declared at globals options
			...scope.through.filter(reference => globalIdentifier.has(reference.identifier.name)),
		];

		for (const {identifier} of references) {
			if (
				isComputedMemberExpressionObject(identifier)
				|| isWindowSpecificAPI(identifier.parent)
				|| isWebWorkerSpecificAPI(identifier.parent)
			) {
				continue;
			}

			// Skip the fix for `typeof window` and `typeof self`
			const isTypeofLegacyGlobal = identifier.parent.type === 'UnaryExpression' && identifier.parent.operator === 'typeof' && identifier.parent.argument === identifier;

			const replacement = isTypeofLegacyGlobal ? 'globalThis.' + identifier.name : 'globalThis';

			yield {
				node: identifier,
				messageId: MESSAGE_ID_ERROR,
				data: {replacement, value: identifier.name},
				fix: fixer => fixer.replaceText(identifier, replacement),
			};
		}
	},
});

/** @type {import('eslint').Rule.RuleModule} */
const config = {
	create,
	meta: {
		type: 'suggestion',
		docs: {
			description: 'Prefer `globalThis` over `window`, `self`, and `global`.',
			recommended: true,
		},
		fixable: 'code',
		hasSuggestions: false,
		messages,
	},
};

export default config;