如何在Javascript中创建此类对象

var person = {
  name: "John",
  age: 30,
  sayHello: function() {
    console.log("Hello!");
  }
};

function Person(name, age) {
  this.name = name;
  this.age = age;
  this.sayHello = function() {
    console.log("Hello!");
  };
}

var person = new Person("John", 30);

function Person(name, age) {
  this.name = name;
  this.age = age;
}

Person.prototype.sayHello = function() {
  console.log("Hello!");
};

var person = new Person("John", 30);

function createPerson(name, age) {
  var person = {};
  person.name = name;
  person.age = age;
  person.sayHello = function() {
    console.log("Hello!");
  };
  return person;
}

var person = createPerson("John", 30);