ObjecthasOwn

ObjecthasOwn is a built‑in static method of the JavaScript Object constructor introduced in ECMAScript 2022. The method checks whether a given object owns a property with a specified key, returning a boolean. It is equivalent to calling the deprecated Object.prototype.hasOwnProperty, but without relying on the prototype chain and without requiring the method to be on the object itself.

The syntax is ObjecthasOwn(object, propertyKey). The first argument is the target object, and the second can be any value that will be coerced to a string or a Symbol. The method returns true if the object has an own property matching that key, and false otherwise. Unlike the older hasOwnProperty, ObjecthasOwn does not invoke getters or non‑enumerable properties that lie in a prototype; it is purely an ownership test.

ObjecthasOwn is designed to address common bugs that arise when objects are used as dictionaries and properties such as "constructor" or "hasOwnProperty" inadvertently shadow builtin properties. By using ObjecthasOwn, developers avoid accidental prototype look‑ups. The method is also defined in Object.prototype.hasOwn in the same way, allowing use as a method call: obj.hasOwn(key).

Support for ObjecthasOwn is available in modern browsers (Chrome, Edge, Firefox, Safari) from version 105 onwards, Node.js from v18.0, and various JavaScript engines. Earlier environments can polyfill the method using Object.prototype.hasOwnProperty or a similar check. Documentation and examples can be found in the ECMAScript specification, as well as in online tutorials covering modern JavaScript features.