详细理解JavaScript:它是一个类、一个函数，还是仅仅是一个变量

Understanding JavaScript in detail: is it a class, a function, or just a variable?

var person = {
     firstName   :"Penelope",
     lastName    :"Barrymore",
     // Since the "this" keyword is used inside the showFullName method below, and the showFullName method is defined on the person object,​
     // "this" will have the value of the person object because the person object will invoke showFullName ()​
     showFullName:function () {
         console.log (this.firstName + " " + this.lastName);
     }
​
 }
​
 person.showFullName (); // Penelope Barrymore

person perObj = new person();
perObj.showFullName();

function showFull() {
    console.log(this.firstName + " " + this.lastName);
}
var person1 = {
    firstName: "Penelope",
    lastName: "Barrymore",
    showFullName: showFull
};
var person2 = {
    firstName: "John",
    lastName: "Smith",
    showFullName: showFull
}
person1.showFullName(); // Penelope Barrymore
person2.showFullName(); // John Smith

var person = function() {
     this.firstName = "";
     this.lastName = "";
} 
person.prototype.showFullName = function () { 
     console.log (this.firstName + " " + this.lastName); 
} 
var perObj = new person();
perObj.firstName = "Penelope";
perObj.lastName = "Barrymore";
perObj.showFullName();

var obj = {
    // Properties and methods
};

// Object initialiser or literal
person = {
  some methods and properties
}
// Called as a constructor
person = new Object({some methods and properties})

这意味着您的person对象继承了原型中特定于对象的方法，如hasOwnProperty()、toString()、valueOf()等。

上次编写的Object constructor不仅可以创建"Hash-like"对象，还可以创建任何其他类型的对象（数组、字符串等）。javascript中的所有对象都是对象，甚至是基元（它们有包装对象，并且有自己的构造函数）。

示例：

persons     = new Object([person_1, person_2, person_3])    
person_age  = new Object(18)
person_name = new Object('John')

我们可以用其他语法编写所有上述表达式：

persons     = new Array(person_1, person_2, person_3) //or      
persons     = [person_1, person_2, person_3]
person_age  = new Number(18) //or    
person_age  = 18
person_name = new String('John') //or    
person_name = 'John'

字符串和数字可以在没有new 的情况下使用适当的全局对象创建

MDN 上的页面

新对象类型

如果需要创建新类型的对象，必须定义新的构造函数并定义原型（ECMAScript 5.1）

NewObjectType = function(arg1, arg2){
   this.arg1 = arg1 //define object's property arg1
   this.arg2 = arg2 //define object's property arg2
   private_function = function(){}
   this.public_function = function(){} //this function can't be inherited, because not in prototype
}
NewObjectType.prototype = {
   constructor : NewObjectType,
   public_inheritable_function_1 : function(){},
   public_inheritable_function_2 : function(){}
}
//creating new instance of NewObjectType:
my_new_object = new NewObjectType(arg1, arg2)
my_new_object instanceof NewObjectType //true
my_new_object instanceof Object        //true, because prototype was created with {} literal, and Object's prototype built into the prototype chain

解释：

调用new NewObjectType时，将创建NewObjectType的新实例。NewObjectType构造函数的Prototype属性将与新实例的隐藏__proto__属性链接。

没有原型的对象

如果需要在没有object方法的情况下创建clear对象，则必须使用create方法在没有原型的情况下进行创建：

person = Object.create(null)

它可能作为简单的键值存储有用

类型，不是从对象继承的

如果需要在原型链中创建没有对象原型的新型对象，您可以使用以下语法：

NewObjectType = function(arg1, arg2){}
NewObjectType.prototype = Object.create(null)
NewObjectType.prototype.constructor = NewObjectType 
NewObjectType.prototype.public_inheritable_function = function(){}
my_new_object = new NewObjectType(arg1, arg2)
my_new_object instanceof NewObjectType //true
my_new_object instanceof Object        //false