hasOwnProperty

Safely checks if an object has its own (non-inherited) property. Uses Object.prototype.hasOwnProperty.call() to avoid prototype pollution and ensure accurate own-property detection, even for objects without Object.prototype in their prototype chain.

Signature

const hasOwnProperty: (value: unknown, key: PropertyKey) => key is keyof typeof value

Parameters

Name	Type	Description
value	-	Object or value to inspect
key	-	Property key to check for ownership

Returns

Type-safe boolean indicating direct property ownership

Examples

Own property detection

import { hasOwnProperty } from '@winglet/common-utils';

const obj = { name: 'John', age: 30 };
console.log(hasOwnProperty(obj, 'name')); // true
console.log(hasOwnProperty(obj, 'toString')); // false (inherited)

const nullObj = Object.create(null);
nullObj.prop = 'value';
console.log(hasOwnProperty(nullObj, 'prop')); // true (safe even without prototype)

Playground

import { hasOwnProperty } from '@winglet/common-utils';

const obj = { name: 'John', age: 30 };
console.log(hasOwnProperty(obj, 'name')); // true
console.log(hasOwnProperty(obj, 'toString')); // false (inherited)

const nullObj = Object.create(null);
nullObj.prop = 'value';
console.log(hasOwnProperty(nullObj, 'prop')); // true (safe even without prototype)