blocks|key|1755892|text|foo.prototype.myFunction+=+function(){alert("me");}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1755893|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>foo.prototype.myFunction = function(){alert("me");}
</code></pre>

blocks|key|1969527|text|据我所知，您不能更改已经构造的对象的[[prototype]]引用。您可以更改原始构造函数的prototype属性，但正如您已经注释的那样，该构造函数是Object的，更改核心JS构造是一件很糟糕的事情。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1969528|不过，您可以为构造的对象创建一个代理对象，以实现所需的附加功能。你也可以通过直接赋值给有问题的对象来monkeypatch额外的方法和行为。|1969529|如果你愿意从不同的角度来看，也许你可以通过其他方式得到你想要的东西:你需要做什么来扰乱原型？|1969530|entityMap^0|I|D|24|6|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|R|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|K|$]]

You cannot change the <code>[[prototype]]</code> reference of already-constructed objects, as far as I know. You could alter the the prototype property of the original constructor function but, as you've already commented, that constructor is <code>Object</code>, and altering core JS constructs is a Bad Thing. 

You could create a proxy object of the constructed object that implements the additional functionality that you need, though. You could also monkeypatch the additional methods and behaviors by assigning directly to the object in question.

Perhaps you can get what you want some other way, if you're willing to approach from a different angle: What do you need to do that involves messing with the prototype?

blocks|key|1756052|text|你可以做火狐，Chrome和Safari支持的foo.__proto__+=+FooClass.prototype，AFAIK。请记住，__proto__属性是非标准的，可能会在某一时刻消失。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1756053|文档：https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/proto。另请参阅http://www.mail-archive.com/jsmentors@googlegroups.com/msg00392.html，了解为什么没有Object.setPrototypeOf()以及为什么不推荐使用__proto__。|1756054|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/proto|1|http://www.mail-archive.com/jsmentors@googlegroups.com/msg00392.html^0|N|Y|1W|9|0|4L|N|5I|9|3|29|0|2H|1W|1|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]|$9|14|A|15|1|16]]|E|$]]|$1|H|3|-4|5|6|7|17|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]|P|$5|K|L|M|E|$N|Q]]]]

You can do <code>foo.__proto__ = FooClass.prototype</code>, AFAIK that's supported by Firefox, Chrome and Safari. Keep in mind that the <code>__proto__</code> property is non-standard and might go away at some point.

Documentation: <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/proto" rel="noreferrer">https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/proto</a>. Also see <a href="http://www.mail-archive.com/jsmentors@googlegroups.com/msg00392.html" rel="noreferrer">http://www.mail-archive.com/jsmentors@googlegroups.com/msg00392.html</a> for an explanation why there is no <code>Object.setPrototypeOf()</code> and why <code>__proto__</code> is deprecated.

blocks|key|1969808|text|可以在对象的实例上使用constructor在位更改对象的原型。我相信这就是你所要求的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1969809|这意味着如果您有作为Foo实例的foo|1969810|function+Foo()+{}

var+foo+=+new+Foo();|code-block|syntax|javascript|1969811|通过执行以下操作，可以将属性bar添加到Foo的所有实例：|1969812|foo.constructor.prototype.bar+=+"bar";|1969813|这是一个展示概念验证的小提琴：http://jsfiddle.net/C2cpw/。我不太确定老的浏览器如何使用这种方法，但我很确定这应该可以很好地完成这项工作。|1969814|如果您的意图是将功能混合到对象中，则此代码片段应该可以完成此任务：|1969815|function+mix()+{
++var+mixins+=+arguments,
++++++i+=+0,+len+=+mixins.length;

++return+{
++++into:+function+(target)+{
++++++var+mixin,+key;

++++++if+(target+==+null)+{
++++++++throw+new+TypeError("Cannot+mix+into+null+or+undefined+values.");
++++++}

++++++for+(;+i+<+len;+i+%2B=+1)+{
++++++++mixin+=+mixins[i];
++++++++for+(key+in+mixin)+{
++++++++++target[key]+=+mixin[key];
++++++++}

++++++++//+Take+care+of+IE+clobbering+`toString`+and+`valueOf`
++++++++if+(mixin+&&+mixin.toString+!==+Object.prototype.toString)+{
++++++++++target.toString+=+mixin.toString;
++++++++}+else+if+(mixin+&&+mixin.valueOf+!==+Object.prototype.valueOf)+{
++++++++++target.valueOf+=+mixin.valueOf;
++++++++}
++++++}
++++++return+target;
++++}
++};
};|1969816|entityMap|0|LINK|mutability|MUTABLE|url|http://jsfiddle.net/C2cpw/^0|B|B|0|A|3|G|3|0|0|E|3|K|3|0|0|F|Q|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|17|8|@$9|18|A|19|B|C]|$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|1C|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1D|8|@$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]]|D|@]|E|$]]|$1|O|3|P|5|J|7|1I|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1J|8|@]|D|@$9|1K|A|1L|1|1M]]|E|$]]|$1|S|3|T|5|6|7|1N|8|@]|D|@]|E|$]]|$1|U|3|V|5|J|7|1O|8|@]|D|@]|E|$K|L]]|$1|W|3|-4|5|6|7|1P|8|@]|D|@]|E|$]]]|X|$Y|$5|Z|10|11|E|$12|13]]]]

You can use <code>constructor</code> on an instance of an object to alter the prototype of an object in-place. I believe this is what you're asking to do.

This means if you have <code>foo</code> which is an instance of <code>Foo</code>:

<pre><code>function Foo() {}

var foo = new Foo();
</code></pre>

You can add a property <code>bar</code> to all instances of <code>Foo</code> by doing the following:

<pre><code>foo.constructor.prototype.bar = "bar";
</code></pre>

Here's a fiddle showing the proof-of-concept: <a href="http://jsfiddle.net/C2cpw/" rel="noreferrer">http://jsfiddle.net/C2cpw/</a>. Not terribly sure how older browsers will fare using this approach, but I'm pretty sure this should do the job pretty well.

If your intention is to mixin functionality into objects, this snippet should do the job:

<pre><code>function mix() {
 var mixins = arguments,
 i = 0, len = mixins.length;

 return {
 into: function (target) {
 var mixin, key;

 if (target == null) {
 throw new TypeError("Cannot mix into null or undefined values.");
 }

 for (; i &lt; len; i += 1) {
 mixin = mixins[i];
 for (key in mixin) {
 target[key] = mixin[key];
 }

 // Take care of IE clobbering `toString` and `valueOf`
 if (mixin &amp;&amp; mixin.toString !== Object.prototype.toString) {
 target.toString = mixin.toString;
 } else if (mixin &amp;&amp; mixin.valueOf !== Object.prototype.valueOf) {
 target.valueOf = mixin.valueOf;
 }
 }
 return target;
 }
 };
};
</code></pre>

blocks|key|1756297|text|如果你知道原型，为什么不把它注入到代码中呢？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1756298|var+foo+=+new+MyPrototype(<%25=+MyData+%25>);|code-block|syntax|javascript|1756299|因此，一旦数据被序列化，您就会得到|1756300|var+foo+=+new+MyPrototype([{"A":"1","B":"2"},{"X":"7","Y":"8"}]);|1756301|现在您只需要一个以数组为参数的构造函数。|1756302|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

If you know the prototype, why not injecting it in the code?

<pre><code>var foo = new MyPrototype(&lt;%= MyData %&gt;);
</code></pre>

So, once the data is serialized, you get

<pre><code>var foo = new MyPrototype([{"A":"1","B":"2"},{"X":"7","Y":"8"}]);
</code></pre>

now you only need a constructor that takes an array as argument.

blocks|key|1969931|text|ES6最后指定了Object.setPrototypeOf(object,+prototype)，它已经在Chrome和Firefox中实现了。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1969932|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/setPrototypeOf^0|8|14|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

ES6 finally specifies <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/setPrototypeOf">Object.setPrototypeOf(object, prototype)</a> which is already implemented in Chrome and Firefox.

blocks|key|1970156|text|如果你想在运行中创建原型，这是一种方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1970157|function+OntheFlyProto+(info){
++++this.items+=+info;
++++this.y+=-1;
++++for(var+i+=+0;+i+<+this.items.length+;+i%2B%2B){
++++++++OntheFlyProto.prototype["get"%2Bthis.items[i].name]+=+function+(){
++++++++++++this.y%2B%2B;
++++++++++++return+this.items[this.y].value;
++++++++}
++++}
}

var+foo+=+[{name:"one",+value:1},{name:"two",+value:2}];
v+=+new+OntheFlyProto(foo);|code-block|syntax|javascript|1970158|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

if you want to create prototype on the fly, this is one of the way

<pre><code>function OntheFlyProto (info){
 this.items = info;
 this.y =-1;
 for(var i = 0; i &lt; this.items.length ; i++){
 OntheFlyProto.prototype["get"+this.items[i].name] = function (){
 this.y++;
 return this.items[this.y].value;
 }
 }
}

var foo = [{name:"one", value:1},{name:"two", value:2}];
v = new OntheFlyProto(foo);
</code></pre>

Suppose I have an object <code>foo</code> in my JavaScript code. <code>foo</code> is a complex object and it is generated somewhere else. How can I change the prototype of the <code>foo</code> object?

My motivation is setting appropriate prototypes to objects serialized from .NET to JavaScript literals.

Suppose that I've written the following JavaScript code within an ASP.NET page.

<pre><code>var foo = &lt;%=MyData %&gt;;
</code></pre>

Suppose that <code>MyData</code> is the result of invoking the .NET <code>JavaScriptSerializer</code> on a <code>Dictionary&lt;string,string&gt;</code> object.

At run-time, this becomes the following:

<pre><code>var foo = [{"A":"1","B":"2"},{"X":"7","Y":"8"}];
</code></pre>

As you can see, <code>foo</code> becomes an array of objects. I would like to be able to initialize <code>foo</code> with an appropriate prototype. I do not want to modify the <code>Object.prototype</code> nor <code>Array.prototype</code>. How can I do this?

How to set the prototype of a JavaScript object that has already been instantiated?

假设我的JavaScript代码中有一个对象foo。foo是一个复杂的对象，它是在其他地方生成的。如何更改foo对象的原型？我的动机是为从.NET序列化为JavaScript文字的对象设置适当的原型。假设我在ASP.NET页面中编写了以下JavaScript代码。var foo = <%=MyData %>;假设MyD...

问如何设置已经实例化的JavaScript对象的原型？
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