SOURCE

class Person {
  constructor(){
    this.name = ""
    this.age = 0
  }
  sayName(){
    console.log('sayName')
  }
}
var o1 = new Person()
console.log(o1.hasOwnProperty('name')) // true
console.log(o1.hasOwnProperty('sayName')) // false

console.log('name' in o1) //true
console.log('sayName' in o1) //true

function hasPrototypeProperty(obj, name){
  return !obj.hasOwnProperty(name) && name in obj;
}
console.log(hasPrototypeProperty(o1, 'sayName'))