[javascript] What is property in hasOwnProperty in JavaScript?

Consider:

if (someVar.hasOwnProperty('someProperty') ) {
 // Do something();
} else {
 // Do somethingElse();
}

What is the right use/explanation of hasOwnProperty('someProperty')?

Why can't we simply use someVar.someProperty to check if an object someVar contains property with name someProperty?

What is a property in this case?

What property does this JavaScript check?

This question is related to javascript object hasownproperty

The answer is