eslint/lib/rules/prefer-reflect.js

An AST-based pattern checker for JavaScript.

/**
 * @fileoverview Rule to suggest using "Reflect" api over Function/Object methods
 * @author Keith Cirkel <http://keithcirkel.co.uk>
 * @deprecated in ESLint v3.9.0
 */
"use strict";

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

/** @type {import('../shared/types').Rule} */
module.exports = {
	meta: {
		type: "suggestion",

		docs: {
			description: "Require `Reflect` methods where applicable",
			recommended: false,
			url: "https://eslint.org/docs/latest/rules/prefer-reflect",
		},

		deprecated: {
			message: "The original intention of this rule was misguided.",
			url: "https://eslint.org/docs/latest/rules/prefer-reflect",
			deprecatedSince: "3.9.0",
			availableUntil: null,
			replacedBy: [],
		},

		schema: [
			{
				type: "object",
				properties: {
					exceptions: {
						type: "array",
						items: {
							enum: [
								"apply",
								"call",
								"delete",
								"defineProperty",
								"getOwnPropertyDescriptor",
								"getPrototypeOf",
								"setPrototypeOf",
								"isExtensible",
								"getOwnPropertyNames",
								"preventExtensions",
							],
						},
						uniqueItems: true,
					},
				},
				additionalProperties: false,
			},
		],

		messages: {
			preferReflect:
				"Avoid using {{existing}}, instead use {{substitute}}.",
		},
	},

	create(context) {
		const existingNames = {
			apply: "Function.prototype.apply",
			call: "Function.prototype.call",
			defineProperty: "Object.defineProperty",
			getOwnPropertyDescriptor: "Object.getOwnPropertyDescriptor",
			getPrototypeOf: "Object.getPrototypeOf",
			setPrototypeOf: "Object.setPrototypeOf",
			isExtensible: "Object.isExtensible",
			getOwnPropertyNames: "Object.getOwnPropertyNames",
			preventExtensions: "Object.preventExtensions",
		};

		const reflectSubstitutes = {
			apply: "Reflect.apply",
			call: "Reflect.apply",
			defineProperty: "Reflect.defineProperty",
			getOwnPropertyDescriptor: "Reflect.getOwnPropertyDescriptor",
			getPrototypeOf: "Reflect.getPrototypeOf",
			setPrototypeOf: "Reflect.setPrototypeOf",
			isExtensible: "Reflect.isExtensible",
			getOwnPropertyNames: "Reflect.getOwnPropertyNames",
			preventExtensions: "Reflect.preventExtensions",
		};

		const exceptions = (context.options[0] || {}).exceptions || [];

		/**
		 * Reports the Reflect violation based on the `existing` and `substitute`
		 * @param {Object} node The node that violates the rule.
		 * @param {string} existing The existing method name that has been used.
		 * @param {string} substitute The Reflect substitute that should be used.
		 * @returns {void}
		 */
		function report(node, existing, substitute) {
			context.report({
				node,
				messageId: "preferReflect",
				data: {
					existing,
					substitute,
				},
			});
		}

		return {
			CallExpression(node) {
				const methodName = (node.callee.property || {}).name;
				const isReflectCall =
					(node.callee.object || {}).name === "Reflect";
				const hasReflectSubstitute = Object.hasOwn(
					reflectSubstitutes,
					methodName,
				);
				const userConfiguredException = exceptions.includes(methodName);

				if (
					hasReflectSubstitute &&
					!isReflectCall &&
					!userConfiguredException
				) {
					report(
						node,
						existingNames[methodName],
						reflectSubstitutes[methodName],
					);
				}
			},
			UnaryExpression(node) {
				const isDeleteOperator = node.operator === "delete";
				const targetsIdentifier = node.argument.type === "Identifier";
				const userConfiguredException = exceptions.includes("delete");

				if (
					isDeleteOperator &&
					!targetsIdentifier &&
					!userConfiguredException
				) {
					report(
						node,
						"the delete keyword",
						"Reflect.deleteProperty",
					);
				}
			},
		};
	},
};