2 * @fileoverview Rule to flag adding properties to native object's prototypes.
8 //------------------------------------------------------------------------------
10 //------------------------------------------------------------------------------
12 const astUtils
= require("./utils/ast-utils");
13 const globals
= require("globals");
15 //------------------------------------------------------------------------------
17 //------------------------------------------------------------------------------
19 /** @type {import('../shared/types').Rule} */
25 description
: "disallow extending native types",
27 url
: "https://eslint.org/docs/rules/no-extend-native"
42 additionalProperties
: false
47 unexpected
: "{{builtin}} prototype is read only, properties should not be added."
53 const config
= context
.options
[0] || {};
54 const exceptions
= new Set(config
.exceptions
|| []);
55 const modifiedBuiltins
= new Set(
56 Object
.keys(globals
.builtin
)
57 .filter(builtin
=> builtin
[0].toUpperCase() === builtin
[0])
58 .filter(builtin
=> !exceptions
.has(builtin
))
62 * Reports a lint error for the given node.
63 * @param {ASTNode} node The node to report.
64 * @param {string} builtin The name of the native builtin being extended.
67 function reportNode(node
, builtin
) {
70 messageId
: "unexpected",
78 * Check to see if the `prototype` property of the given object
79 * identifier node is being accessed.
80 * @param {ASTNode} identifierNode The Identifier representing the object
82 * @returns {boolean} True if the identifier is the object of a
83 * MemberExpression and its `prototype` property is being accessed,
86 function isPrototypePropertyAccessed(identifierNode
) {
89 identifierNode
.parent
&&
90 identifierNode
.parent
.type
=== "MemberExpression" &&
91 identifierNode
.parent
.object
=== identifierNode
&&
92 astUtils
.getStaticPropertyName(identifierNode
.parent
) === "prototype"
97 * Check if it's an assignment to the property of the given node.
98 * Example: `*.prop = 0` // the `*` is the given node.
99 * @param {ASTNode} node The node to check.
100 * @returns {boolean} True if an assignment to the property of the node.
102 function isAssigningToPropertyOf(node
) {
104 node
.parent
.type
=== "MemberExpression" &&
105 node
.parent
.object
=== node
&&
106 node
.parent
.parent
.type
=== "AssignmentExpression" &&
107 node
.parent
.parent
.left
=== node
.parent
112 * Checks if the given node is at the first argument of the method call of `Object.defineProperty()` or `Object.defineProperties()`.
113 * @param {ASTNode} node The node to check.
114 * @returns {boolean} True if the node is at the first argument of the method call of `Object.defineProperty()` or `Object.defineProperties()`.
116 function isInDefinePropertyCall(node
) {
118 node
.parent
.type
=== "CallExpression" &&
119 node
.parent
.arguments
[0] === node
&&
120 astUtils
.isSpecificMemberAccess(node
.parent
.callee
, "Object", /^definePropert(?:y|ies)$/u)
125 * Check to see if object prototype access is part of a prototype
126 * extension. There are three ways a prototype can be extended:
127 * 1. Assignment to prototype property (Object.prototype.foo = 1)
128 * 2. Object.defineProperty()/Object.defineProperties() on a prototype
129 * If prototype extension is detected, report the AssignmentExpression
130 * or CallExpression node.
131 * @param {ASTNode} identifierNode The Identifier representing the object
132 * which prototype is being accessed and possibly extended.
135 function checkAndReportPrototypeExtension(identifierNode
) {
136 if (!isPrototypePropertyAccessed(identifierNode
)) {
137 return; // This is not `*.prototype` access.
141 * `identifierNode.parent` is a MemberExpression `*.prototype`.
142 * If it's an optional member access, it may be wrapped by a `ChainExpression` node.
144 const prototypeNode
=
145 identifierNode
.parent
.parent
.type
=== "ChainExpression"
146 ? identifierNode
.parent
.parent
147 : identifierNode
.parent
;
149 if (isAssigningToPropertyOf(prototypeNode
)) {
151 // `*.prototype` -> MemberExpression -> AssignmentExpression
152 reportNode(prototypeNode
.parent
.parent
, identifierNode
.name
);
153 } else if (isInDefinePropertyCall(prototypeNode
)) {
155 // `*.prototype` -> CallExpression
156 reportNode(prototypeNode
.parent
, identifierNode
.name
);
163 const globalScope
= context
.getScope();
165 modifiedBuiltins
.forEach(builtin
=> {
166 const builtinVar
= globalScope
.set.get(builtin
);
168 if (builtinVar
&& builtinVar
.references
) {
169 builtinVar
.references
170 .map(ref
=> ref
.identifier
)
171 .forEach(checkAndReportPrototypeExtension
);