javascript hasownproperty

var person = {	
  	"first_name": "Bob",
	"last_name": "Dylan"
};
person.hasOwnProperty('first_name'); //returns true
person.hasOwnProperty('age'); //returns falsevar x = {
    y: 10
};
console.log(x.hasOwnProperty("y")); //true
console.log(x.hasOwnProperty("z")); //falsevar person = {'first_name': 'bill','age':20};

if ( person.hasOwnProperty('first_name') ) {
    //person has a first_name property
}
if (someVar.hasOwnProperty('someProperty') ) {
 // do something();
} else {
 // do somethingElse();
}The hasOwnProperty() method returns a boolean indicating whether the object has the specified property as its own property (as opposed to inheriting it).

const object1 = {};
object1.property1 = 42;

console.log(object1.hasOwnProperty('property1'));
// expected output: true

console.log(object1.hasOwnProperty('toString'));
// expected output: false
//hasOwnPropertydevuelve un valor booleano que indica si el objeto al que está llamando tiene una propiedad con el nombre del argumento. Por ejemplo:

var x = {
y: 10};
console.log(x.hasOwnProperty("y")); //true
console.log(x.hasOwnProperty("z")); //false