[d565449] | 1 | /**
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| 2 | * @fileoverview Rule to flag adding properties to native object's prototypes.
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| 3 | * @author David Nelson
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| 4 | */
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| 5 |
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| 6 | "use strict";
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| 7 |
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| 8 | //------------------------------------------------------------------------------
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| 9 | // Requirements
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| 10 | //------------------------------------------------------------------------------
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| 11 |
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| 12 | const astUtils = require("./utils/ast-utils");
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| 13 | const globals = require("globals");
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| 14 |
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| 15 | //------------------------------------------------------------------------------
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| 16 | // Rule Definition
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| 17 | //------------------------------------------------------------------------------
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| 18 |
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| 19 | /** @type {import('../shared/types').Rule} */
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| 20 | module.exports = {
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| 21 | meta: {
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| 22 | type: "suggestion",
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| 23 |
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| 24 | docs: {
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| 25 | description: "Disallow extending native types",
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| 26 | recommended: false,
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| 27 | url: "https://eslint.org/docs/latest/rules/no-extend-native"
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| 28 | },
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| 29 |
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| 30 | schema: [
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| 31 | {
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| 32 | type: "object",
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| 33 | properties: {
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| 34 | exceptions: {
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| 35 | type: "array",
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| 36 | items: {
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| 37 | type: "string"
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| 38 | },
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| 39 | uniqueItems: true
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| 40 | }
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| 41 | },
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| 42 | additionalProperties: false
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| 43 | }
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| 44 | ],
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| 45 |
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| 46 | messages: {
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| 47 | unexpected: "{{builtin}} prototype is read only, properties should not be added."
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| 48 | }
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| 49 | },
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| 50 |
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| 51 | create(context) {
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| 52 |
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| 53 | const config = context.options[0] || {};
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| 54 | const sourceCode = context.sourceCode;
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| 55 | const exceptions = new Set(config.exceptions || []);
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| 56 | const modifiedBuiltins = new Set(
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| 57 | Object.keys(globals.builtin)
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| 58 | .filter(builtin => builtin[0].toUpperCase() === builtin[0])
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| 59 | .filter(builtin => !exceptions.has(builtin))
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| 60 | );
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| 61 |
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| 62 | /**
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| 63 | * Reports a lint error for the given node.
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| 64 | * @param {ASTNode} node The node to report.
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| 65 | * @param {string} builtin The name of the native builtin being extended.
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| 66 | * @returns {void}
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| 67 | */
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| 68 | function reportNode(node, builtin) {
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| 69 | context.report({
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| 70 | node,
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| 71 | messageId: "unexpected",
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| 72 | data: {
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| 73 | builtin
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| 74 | }
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| 75 | });
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| 76 | }
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| 77 |
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| 78 | /**
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| 79 | * Check to see if the `prototype` property of the given object
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| 80 | * identifier node is being accessed.
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| 81 | * @param {ASTNode} identifierNode The Identifier representing the object
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| 82 | * to check.
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| 83 | * @returns {boolean} True if the identifier is the object of a
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| 84 | * MemberExpression and its `prototype` property is being accessed,
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| 85 | * false otherwise.
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| 86 | */
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| 87 | function isPrototypePropertyAccessed(identifierNode) {
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| 88 | return Boolean(
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| 89 | identifierNode &&
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| 90 | identifierNode.parent &&
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| 91 | identifierNode.parent.type === "MemberExpression" &&
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| 92 | identifierNode.parent.object === identifierNode &&
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| 93 | astUtils.getStaticPropertyName(identifierNode.parent) === "prototype"
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| 94 | );
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| 95 | }
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| 96 |
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| 97 | /**
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| 98 | * Check if it's an assignment to the property of the given node.
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| 99 | * Example: `*.prop = 0` // the `*` is the given node.
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| 100 | * @param {ASTNode} node The node to check.
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| 101 | * @returns {boolean} True if an assignment to the property of the node.
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| 102 | */
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| 103 | function isAssigningToPropertyOf(node) {
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| 104 | return (
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| 105 | node.parent.type === "MemberExpression" &&
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| 106 | node.parent.object === node &&
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| 107 | node.parent.parent.type === "AssignmentExpression" &&
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| 108 | node.parent.parent.left === node.parent
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| 109 | );
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| 110 | }
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| 111 |
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| 112 | /**
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| 113 | * Checks if the given node is at the first argument of the method call of `Object.defineProperty()` or `Object.defineProperties()`.
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| 114 | * @param {ASTNode} node The node to check.
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| 115 | * @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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| 116 | */
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| 117 | function isInDefinePropertyCall(node) {
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| 118 | return (
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| 119 | node.parent.type === "CallExpression" &&
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| 120 | node.parent.arguments[0] === node &&
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| 121 | astUtils.isSpecificMemberAccess(node.parent.callee, "Object", /^definePropert(?:y|ies)$/u)
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| 122 | );
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| 123 | }
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| 124 |
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| 125 | /**
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| 126 | * Check to see if object prototype access is part of a prototype
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| 127 | * extension. There are three ways a prototype can be extended:
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| 128 | * 1. Assignment to prototype property (Object.prototype.foo = 1)
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| 129 | * 2. Object.defineProperty()/Object.defineProperties() on a prototype
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| 130 | * If prototype extension is detected, report the AssignmentExpression
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| 131 | * or CallExpression node.
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| 132 | * @param {ASTNode} identifierNode The Identifier representing the object
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| 133 | * which prototype is being accessed and possibly extended.
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| 134 | * @returns {void}
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| 135 | */
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| 136 | function checkAndReportPrototypeExtension(identifierNode) {
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| 137 | if (!isPrototypePropertyAccessed(identifierNode)) {
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| 138 | return; // This is not `*.prototype` access.
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| 139 | }
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| 140 |
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| 141 | /*
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| 142 | * `identifierNode.parent` is a MemberExpression `*.prototype`.
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| 143 | * If it's an optional member access, it may be wrapped by a `ChainExpression` node.
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| 144 | */
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| 145 | const prototypeNode =
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| 146 | identifierNode.parent.parent.type === "ChainExpression"
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| 147 | ? identifierNode.parent.parent
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| 148 | : identifierNode.parent;
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| 149 |
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| 150 | if (isAssigningToPropertyOf(prototypeNode)) {
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| 151 |
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| 152 | // `*.prototype` -> MemberExpression -> AssignmentExpression
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| 153 | reportNode(prototypeNode.parent.parent, identifierNode.name);
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| 154 | } else if (isInDefinePropertyCall(prototypeNode)) {
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| 155 |
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| 156 | // `*.prototype` -> CallExpression
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| 157 | reportNode(prototypeNode.parent, identifierNode.name);
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| 158 | }
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| 159 | }
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| 160 |
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| 161 | return {
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| 162 |
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| 163 | "Program:exit"(node) {
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| 164 | const globalScope = sourceCode.getScope(node);
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| 165 |
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| 166 | modifiedBuiltins.forEach(builtin => {
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| 167 | const builtinVar = globalScope.set.get(builtin);
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| 168 |
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| 169 | if (builtinVar && builtinVar.references) {
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| 170 | builtinVar.references
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| 171 | .map(ref => ref.identifier)
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| 172 | .forEach(checkAndReportPrototypeExtension);
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| 173 | }
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| 174 | });
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| 175 | }
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| 176 | };
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| 177 |
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| 178 | }
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| 179 | };
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