一个案例中的对象相同，另一个案例中的对象不同？

Question

我想知道在下面的代码中处理复制一个对象到另一个对象上发生了什么。在某些情况下，他们的行为就像是改变另一个的相同对象。我发现很多关于JavaScript对象如何通过引用被复制的帖子，所以它们实际上是相同的对象。例如，从http://www.w3schools.com/js/js_object_definition.asp：

var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"} 
var x = person; // This will not create a copy of person. 
x.age = 10; // This will change both x.age and person.age 

The object x is not a copy of person. It is person. Both x and person 
is the same object. Any changes to x will also change person, because 
x and person are the same object. 

不过，我也发现那里的对象似乎是单独的对象的情况。在一种情况下，它如何表现为相同的对象，但在另一种情况下，却有不同的对象？我将不胜感激情况任何光：

例子：http://codepen.io/gratiafide/pen/yagQGr?editors=1010#0

HTML：

<div id="app"> 
    <my-component> 
    </my-component> 
</div> 

JS：

var MyComponent = Vue.extend({ 
    template: '<div v-on:click="test()" class="red">1. Click here to copy the name object to message and change the value of name to see if the value of message gets changed also. (It does not).</div> message: {{ message | json}} <br> name: {{ name | json}}<div v-on:click="test2()" class="red">2. Now click here to see if updating the name object also changes the message object. It does! Why here and not in #1?</div><div v-on:click="test3()" class="red">3. Click here to see yet another way of updating the name object also changes the message object. Why here and not in #1?</div>', 

    data: function() { 
    return { 
    message: {}, 
    name: {} 
    } 
    }, 

    ready: function(){ 
    this.message = {}; 
    }, 
    methods: { 
    test: function(){ 
     this.message = {'t1':"m1"}; 
     this.name = this.message; 
     this.name = {'t2':"m2"}; 
    }, 
    test2: function(){ 
     this.message = {'t1':"m1"}; 
     this.name = this.message; 
     for (var key in this.name) { 
       this.name[key] = ''; 
      } 
    }, 
    test3: function(){ 
     this.message = {'t1':"m1"}; 
     this.name = this.message; 
     Vue.set(this.name, 't1', 'm2'); 
    } 
    } 
}); 

Vue.component('my-component', MyComponent); 

new Vue({ 
    el: '#app' 
}); 

CSS：

@import url(https://fonts.googleapis.com/css?family=Open+Sans); 

.red{ 
    color:red; 
} 

body { 
    font-family: 'Open Sans', sans-serif; 
    background: rgba(0,0,0,.5); 
    margin: 0; 
} 

#app { 
    width: 500px; 
    margin: 0 auto; 
    padding: 10px 20px; 
    background: rgba(255,255,255,.9); 
} 

Answer 1

基本上，你问荷兰国际集团这三者之间的区别：

this.message = {'t1':"m1"}; 
this.name = this.message; 

#1: 
this.name = {'t2':"m2"}; 

#2 
for (var key in this.name) { 
    this.name[key] = ''; 
} 

#3 
Vue.set(this.name, 't1', 'm2'); 

在第一种情况下，因为你分配一个全新的对象this.name你会不会改变this.message。这个新对象（{'t2':"m2"}）与this.message完全无关。

做的也许是你所想/想法是：

this.name.t2 = "m2"; 

哪个做同样的＃2，＃3，影响this.message，因为this.name仍然指的是同一个对象。

要设定新的属性到现有的对象，从另外一个对象，你可以在支持此功能的浏览器使用Object.assign：

Object.assign(this.name, {'t2':"m2"}); 

Answer 2

有2种类型的变量，值和引用。所有的原语（即字符串，数字和布尔值）都是按值存储的，其他所有的都是由引用存储的，并且可以具有属性。

var a,b; 
 
a={c:1}; 
 
b=a; 
 
console.log (b===a); // true; 
 

 
b={c:1}; // note that b is now being assigned a new reference. 
 
console.log (b===a); // false; 
 

 
a=b; // now a is being assigned the reference of b. 
 
console.log (b===a); // true; 
 

 
a.c=2; //note that it is the property of a (c) got changed, not a itself. 
 
console.log (b===a); // true; 
 

 
a.a = a; //now a has a property (a) that stores the reference of a. 
 
console.log(a === a.a); 
 
console.log(a.a === a.a.a); 
 
console.log(a.a === a.a.a.a.a.a.a.a.a); 
 
a.a.a.a.a.a.a.a.a.a.a.c = 10; 
 
console.log(a.c)//10;

有不同的方法来声明变量，但这不是问题的范围。