Class-based object-oriented languages, such as Java and C++:
1.class定義了所有的屬性
2.instance來實現class

A prototype-based language, such as JavaScript
1.只有object,任何object可以指定自己的屬性,無論是在創建還是運行時
1.任何object可以以prototype形式和其他的object關聯,來共享屬性

function Employee() {this.name = '';this.dept = 'general';
}

public class Employee {public String name = "";public String dept = "general";
}

繼承

function Manager() {Employee.call(this);this.reports = [];
}
Manager.prototype = Object.create(Employee.prototype);
Manager.prototype.constructor = Manager;function WorkerBee() {Employee.call(this);this.projects = [];
}
WorkerBee.prototype = Object.create(Employee.prototype);
WorkerBee.prototype.constructor = WorkerBee;

public class Manager extends Employee {public Employee[] reports = new Employee[0];
}public class WorkerBee extends Employee {public String[] projects = new String[0];
}

參考:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Details_of_the_Object_Model