objectPrototypeBuiltIns

Reports direct calls to Object.prototype methods on object instances.

✅ This rule is included in the ts logical and logicalStrict presets.

Objects can have properties that shadow the built-in methods from Object.prototype such as hasOwnProperty, isPrototypeOf, and propertyIsEnumerable. Additionally, objects created with Object.create(null) do not inherit from Object.prototype and will not have these methods. Calling these methods directly on objects can lead to errors or security vulnerabilities.

const 
const hasKey: boolean
hasKey = 
const object: Record<string, unknown>
object.
Object.hasOwnProperty(v: PropertyKey): boolean
Determines whether an object has a property with the specified name.
@param ― v A property name.
hasOwnProperty("key");

const 
const isPrototypeOf: boolean
isPrototypeOf = 
const object: Record<string, unknown>
object.
Object.isPrototypeOf(v: Object): boolean
Determines whether an object exists in another object's prototype chain.
@param ― v Another object whose prototype chain is to be checked.
isPrototypeOf(
const other: Record<string, unknown>
other);

const 
const isEnumerable: boolean
isEnumerable = 
const object: Record<string, unknown>
object.
Object.propertyIsEnumerable(v: PropertyKey): boolean
Determines whether a specified property is enumerable.
@param ― v A property name.
propertyIsEnumerable("prop");

const 
const hasKey: boolean
hasKey = 
var Object: ObjectConstructor
Provides functionality common to all JavaScript objects.
Object.
ObjectConstructor.prototype: Object
A reference to the prototype for a class of objects.
prototype.
Object.hasOwnProperty(v: PropertyKey): boolean
Determines whether an object has a property with the specified name.
@param ― v A property name.
hasOwnProperty.
CallableFunction.call<Record<string, unknown>, [string], boolean>(this: (this: Record<string, unknown>, args_0: string) => boolean, thisArg: Record<string, unknown>, args_0: string): boolean
Calls the function with the specified object as the this value and the specified rest arguments as the arguments.
@param ― thisArg The object to be used as the this object.
@param ― args Argument values to be passed to the function.
call(
const object: Record<string, unknown>
object, "key");

const 
const isPrototypeOf: boolean
isPrototypeOf = 
var Object: ObjectConstructor
Provides functionality common to all JavaScript objects.
Object.
ObjectConstructor.prototype: Object
A reference to the prototype for a class of objects.
prototype.
Object.isPrototypeOf(v: Object): boolean
Determines whether an object exists in another object's prototype chain.
@param ― v Another object whose prototype chain is to be checked.
isPrototypeOf.
CallableFunction.call<Record<string, unknown>, [Record<string, unknown>], boolean>(this: (this: Record<string, unknown>, args_0: Record<string, unknown>) => boolean, thisArg: Record<string, unknown>, args_0: Record<string, unknown>): boolean
Calls the function with the specified object as the this value and the specified rest arguments as the arguments.
@param ― thisArg The object to be used as the this object.
@param ― args Argument values to be passed to the function.
call(
const object: Record<string, unknown>
object, 
const other: Record<string, unknown>
other);

const 
const isEnumerable: boolean
isEnumerable = {}.
Object.propertyIsEnumerable(v: PropertyKey): boolean
Determines whether a specified property is enumerable.
@param ― v A property name.
propertyIsEnumerable.
CallableFunction.call<Record<string, unknown>, [string], boolean>(this: (this: Record<string, unknown>, args_0: string) => boolean, thisArg: Record<string, unknown>, args_0: string): boolean
Calls the function with the specified object as the this value and the specified rest arguments as the arguments.
@param ― thisArg The object to be used as the this object.
@param ― args Argument values to be passed to the function.
call(
const object: Record<string, unknown>
object, "prop");

Options

This rule is not configurable.

When Not To Use It

If code only uses objects with hardcoded keys and never uses Object.create(null) or allows user-controlled object keys, this rule might not be necessary. Alternately, if your codebase overrides these properties -which is a dangerous legacy pattern most runtimes recommend against- you might not be able to enable this rule.

Equivalents in Other Linters

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objectPrototypeBuiltIns

Examples

Options

When Not To Use It

Further Reading

Equivalents in Other Linters