181 lines
		
	
	
		
			5.3 KiB
		
	
	
	
		
			JavaScript
		
	
	
		
			Executable File
		
	
	
	
	
			
		
		
	
	
			181 lines
		
	
	
		
			5.3 KiB
		
	
	
	
		
			JavaScript
		
	
	
		
			Executable File
		
	
	
	
	
/**
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 * @fileoverview Rule to flag adding properties to native object's prototypes.
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 * @author David Nelson
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 */
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require("./utils/ast-utils");
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../types').Rule.RuleModule} */
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module.exports = {
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	meta: {
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		type: "suggestion",
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		defaultOptions: [{ exceptions: [] }],
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		docs: {
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			description: "Disallow extending native types",
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			recommended: false,
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			url: "https://eslint.org/docs/latest/rules/no-extend-native",
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		},
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		schema: [
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			{
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				type: "object",
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				properties: {
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					exceptions: {
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						type: "array",
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						items: {
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							type: "string",
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						},
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						uniqueItems: true,
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					},
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				},
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				additionalProperties: false,
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			},
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		],
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		messages: {
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			unexpected:
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				"{{builtin}} prototype is read only, properties should not be added.",
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		},
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	},
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	create(context) {
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		const sourceCode = context.sourceCode;
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		const exceptions = new Set(context.options[0].exceptions);
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		const modifiedBuiltins = new Set(
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			Object.keys(astUtils.ECMASCRIPT_GLOBALS)
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				.filter(builtin => builtin[0].toUpperCase() === builtin[0])
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				.filter(builtin => !exceptions.has(builtin)),
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		);
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		/**
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		 * Reports a lint error for the given node.
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		 * @param {ASTNode} node The node to report.
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		 * @param {string} builtin The name of the native builtin being extended.
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		 * @returns {void}
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		 */
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		function reportNode(node, builtin) {
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			context.report({
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				node,
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				messageId: "unexpected",
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				data: {
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					builtin,
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				},
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			});
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		}
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		/**
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		 * Check to see if the `prototype` property of the given object
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		 * identifier node is being accessed.
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		 * @param {ASTNode} identifierNode The Identifier representing the object
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		 * to check.
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		 * @returns {boolean} True if the identifier is the object of a
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		 * MemberExpression and its `prototype` property is being accessed,
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		 * false otherwise.
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		 */
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		function isPrototypePropertyAccessed(identifierNode) {
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			return Boolean(
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				identifierNode &&
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					identifierNode.parent &&
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					identifierNode.parent.type === "MemberExpression" &&
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					identifierNode.parent.object === identifierNode &&
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					astUtils.getStaticPropertyName(identifierNode.parent) ===
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						"prototype",
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			);
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		}
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		/**
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		 * Check if it's an assignment to the property of the given node.
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		 * Example: `*.prop = 0` // the `*` is the given node.
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		 * @param {ASTNode} node The node to check.
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		 * @returns {boolean} True if an assignment to the property of the node.
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		 */
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		function isAssigningToPropertyOf(node) {
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			return (
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				node.parent.type === "MemberExpression" &&
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				node.parent.object === node &&
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				node.parent.parent.type === "AssignmentExpression" &&
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				node.parent.parent.left === node.parent
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			);
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		}
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		/**
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		 * Checks if the given node is at the first argument of the method call of `Object.defineProperty()` or `Object.defineProperties()`.
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		 * @param {ASTNode} node The node to check.
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		 * @returns {boolean} True if the node is at the first argument of the method call of `Object.defineProperty()` or `Object.defineProperties()`.
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		 */
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		function isInDefinePropertyCall(node) {
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			return (
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				node.parent.type === "CallExpression" &&
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				node.parent.arguments[0] === node &&
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				astUtils.isSpecificMemberAccess(
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					node.parent.callee,
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					"Object",
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					/^definePropert(?:y|ies)$/u,
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				)
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			);
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		}
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		/**
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		 * Check to see if object prototype access is part of a prototype
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		 * extension. There are three ways a prototype can be extended:
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		 * 1. Assignment to prototype property (Object.prototype.foo = 1)
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		 * 2. Object.defineProperty()/Object.defineProperties() on a prototype
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		 * If prototype extension is detected, report the AssignmentExpression
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		 * or CallExpression node.
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		 * @param {ASTNode} identifierNode The Identifier representing the object
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		 * which prototype is being accessed and possibly extended.
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		 * @returns {void}
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		 */
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		function checkAndReportPrototypeExtension(identifierNode) {
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			if (!isPrototypePropertyAccessed(identifierNode)) {
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				return; // This is not `*.prototype` access.
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			}
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			/*
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			 * `identifierNode.parent` is a MemberExpression `*.prototype`.
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			 * If it's an optional member access, it may be wrapped by a `ChainExpression` node.
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			 */
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			const prototypeNode =
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				identifierNode.parent.parent.type === "ChainExpression"
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					? identifierNode.parent.parent
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					: identifierNode.parent;
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			if (isAssigningToPropertyOf(prototypeNode)) {
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				// `*.prototype` -> MemberExpression -> AssignmentExpression
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				reportNode(prototypeNode.parent.parent, identifierNode.name);
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			} else if (isInDefinePropertyCall(prototypeNode)) {
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				// `*.prototype` -> CallExpression
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				reportNode(prototypeNode.parent, identifierNode.name);
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			}
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		}
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		return {
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			"Program:exit"(node) {
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				const globalScope = sourceCode.getScope(node);
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				modifiedBuiltins.forEach(builtin => {
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					const builtinVar = globalScope.set.get(builtin);
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					if (builtinVar && builtinVar.references) {
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						builtinVar.references
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							.map(ref => ref.identifier)
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							.forEach(checkAndReportPrototypeExtension);
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					}
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				});
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			},
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		};
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	},
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};
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