Above - screenshot from MDN’s Object.hasOwn() documentation.

If you so far waited to make the switch because of “lack of wide support”:
Since April 2025 - even the Android native browser and Android Firefox support it by now (and there has been wide support for all major browsers since 2022).

Why use any of them?

You want to check if a property exist directly on an object. The most foolproof way to do that was to call .hasOwnProperty on the object itself.

Why not just use if (obj.prop) or (if “prop” in obj)?

The reason for the first case, is, this: { prop: null } will return false even though prop does exist in the object (same goes for { prop: undefined }, { prop: false } or any falsy value.

The reason for the second case is, in searches for the property through the entire prototype chain - sometimes you want this, but if you intended to check the existence of the property directly on the object, you might encounter undesirable results (maybe the property was defined someplace else on the chain, by you, or a 3rd party?).

Only .hasOwnProperty was the safest way to check if a property directly exist on an object.

So, what’s wrong with it?

It’s overridable

Either with a simple { hasOwnProperty() { console.log(“Ha Ha!”); } } or with a more “low-level” Object.defineProperty

Proxy getters will add an overhead

If you Proxy an object and add a custom getter - it will be called every time you’ll call hasOwnProperty - which will introduce an annoying overhead, and checking if a property exists on an object is a pretty common thing to do in Javascript.

It makes more overall sense, semantically, abstractly

hasOwnPrototype is a method defined on the prototype of Object which all things in Javascript inherit (well… except for null which only “thinks” it’s an object (actually the reason that typeof null returns object is historically interesting, but out of the scope of this article), or undefined).
But, it kinda makes sense that the action of “checking if a property exists on an object” should be a static method (like Object.keys or Object.values and so on).

So… no more excuses

Migrate to Object.hasOwn today!