blocks|key|1150250|text|不，对象没有内置的标识符，但您可以通过修改对象原型来添加一个。下面是你如何做到这一点的一个例子：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1150251|(function()+{
++++var+id+=+0;

++++function+generateId()+{+return+id%2B%2B;+};

++++Object.prototype.id+=+function()+{
++++++++var+newId+=+generateId();

++++++++this.id+=+function()+{+return+newId;+};

++++++++return+newId;
++++};
})();|code-block|syntax|javascript|1150252|也就是说，一般来说，修改对象原型被认为是非常糟糕的做法。相反，我建议您根据需要手动为对象分配id，或者按照其他人的建议使用touch函数。|offset|length|style|CODE|1150253|entityMap^0|0|0|1P|5|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]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

No, objects don't have a built in identifier, though you can add one by modifying the object prototype. Here's an example of how you might do that:

<pre><code>(function() {
 var id = 0;

 function generateId() { return id++; };

 Object.prototype.id = function() {
 var newId = generateId();

 this.id = function() { return newId; };

 return newId;
 };
})();
</code></pre>

That said, in general modifying the object prototype is considered very bad practice. I would instead recommend that you manually assign an id to objects as needed or use a <code>touch</code> function as others have suggested.

blocks|key|1150301|text|实际上，您不需要修改object原型。下面的代码可以足够有效地“获取”任何对象的唯一ids。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1150302|var+__next_objid=1;
function+objectId(obj)+{
++++if+(obj==null)+return+null;
++++if+(obj.__obj_id==null)+obj.__obj_id=__next_objid%2B%2B;
++++return+obj.__obj_id;
}|code-block|syntax|javascript|1150303|entityMap^0|A|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

Actually, you don't need to modify the <code>object</code> prototype. The following should work to 'obtain' unique ids for any object, efficiently enough.

<pre><code>var __next_objid=1;
function objectId(obj) {
 if (obj==null) return null;
 if (obj.__obj_id==null) obj.__obj_id=__next_objid++;
 return obj.__obj_id;
}
</code></pre>

blocks|key|1365430|text|我刚刚发现了这一点，我想我应该补充一下我的想法。正如其他人所建议的那样，我建议手动添加ID，但如果您真的想要与所描述的内容接近的内容，您可以使用以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1365431|var+objectId+=+(function+()+{
++++var+allObjects+=+[];

++++var+f+=+function(obj)+{
++++++++if+(allObjects.indexOf(obj)+===+-1)+{
++++++++++++allObjects.push(obj);
++++++++}
++++++++return+allObjects.indexOf(obj);
++++}
++++f.clear+=+function()+{
++++++allObjects+=+[];
++++};
++++return+f;
})();|code-block|syntax|javascript|1365432|您可以通过调用objectId(obj)来获取任何对象的ID。然后，如果您希望id成为对象的属性，则可以扩展原型：|offset|length|style|CODE|1365433|Object.prototype.id+=+function+()+{
++++return+objectId(this);
}|1365434|或者，您可以通过添加类似的函数作为方法来手动为每个对象添加ID。|1365435|主要的警告是，这将防止垃圾收集器在对象退出作用域时销毁对象……它们永远不会脱离allObjects数组的范围，因此您可能会发现内存泄漏是一个问题。如果设置为使用此方法，则应仅出于调试目的而这样做。需要时，您可以执行objectId.clear()来清除allObjects并让GC完成其工作(但从那时起，对象ids将全部重置)。|1365436|entityMap^0|0|0|7|D|0|0|0|13|A|2Z|G|3I|A|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@$I|X|J|Y|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|11|8|@$I|12|J|13|K|L]|$I|14|J|15|K|L]|$I|16|J|17|K|L]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|T|$]]

I've just come across this, and thought I'd add my thoughts. As others have suggested, I'd recommend manually adding IDs, but if you really want something close to what you've described, you could use this:

<pre><code>var objectId = (function () {
 var allObjects = [];

 var f = function(obj) {
 if (allObjects.indexOf(obj) === -1) {
 allObjects.push(obj);
 }
 return allObjects.indexOf(obj);
 }
 f.clear = function() {
 allObjects = [];
 };
 return f;
})();
</code></pre>

You can get any object's ID by calling <code>objectId(obj)</code>. Then if you want the id to be a property of the object, you can either extend the prototype:

<pre><code>Object.prototype.id = function () {
 return objectId(this);
}
</code></pre>

or you can manually add an ID to each object by adding a similar function as a method.

The major caveat is that this will prevent the garbage collector from destroying objects when they drop out of scope... they will never drop out of the scope of the <code>allObjects</code> array, so you might find memory leaks are an issue. If your set on using this method, you should do so for debugging purpose only. When needed, you can do <code>objectId.clear()</code> to clear the <code>allObjects</code> and let the GC do its job (but from that point the object ids will all be reset).

blocks|key|1150383|text|如果希望在不修改底层对象的情况下查找/关联具有唯一标识符的对象，则可以使用WeakMap|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1150384|//+Note+that+object+must+be+an+object+or+array,
//+NOT+a+primitive+value+like+string,+number,+etc.
var+objIdMap=new+WeakMap,+objectCount+=+0;
function+objectId(object){
++if+(!objIdMap.has(object))+objIdMap.set(object,%2B%2BobjectCount);
++return+objIdMap.get(object);
}

var+o1={},+o2={},+o3={a:1},+o4={a:1};
console.log(+objectId(o1)+)+//+1
console.log(+objectId(o2)+)+//+2
console.log(+objectId(o1)+)+//+1
console.log(+objectId(o3)+)+//+3
console.log(+objectId(o4)+)+//+4
console.log(+objectId(o3)+)+//+3|code-block|syntax|javascript|1150385|使用WeakMap而不是Map可以确保对象仍然可以被垃圾收集。|1150386|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap^0|11|7|11|7|0|0|0|2|7|C|3|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|G|5|H|7|10|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|N|$O|$5|P|Q|R|E|$S|T]]]]

If you want to lookup/associate an object with a unique identifier without modifying the underlying object, you can use a <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap" rel="noreferrer"><code>WeakMap</code></a>:
<pre class="lang-js prettyprint-override"><code>// Note that object must be an object or array,
// NOT a primitive value like string, number, etc.
var objIdMap=new WeakMap, objectCount = 0;
function objectId(object){
 if (!objIdMap.has(object)) objIdMap.set(object,++objectCount);
 return objIdMap.get(object);
}

var o1={}, o2={}, o3={a:1}, o4={a:1};
console.log( objectId(o1) ) // 1
console.log( objectId(o2) ) // 2
console.log( objectId(o1) ) // 1
console.log( objectId(o3) ) // 3
console.log( objectId(o4) ) // 4
console.log( objectId(o3) ) // 3
</code></pre>
Using a <code>WeakMap</code> instead of <code>Map</code> ensures that the objects can still be garbage-collected.

blocks|key|1150396|text|​|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1150397|const+log+=+console.log;

function*+generateId()+{
++for(let+i+=+0;+;+%2B%2Bi)+{
++++yield+i;
++}
}

const+idGenerator+=+generateId();

const+ObjectWithId+=+new+Proxy(Object,+{
++construct(target,+args)+{
++++const+instance+=+Reflect.construct(target,+args);
++++instance['id']+=+idGenerator.next().value;
++++return+instance;
++}
})

const+myObject+=+new+ObjectWithId({
++name:+'@@NativeObject'
});

log(myObject.id);|code-block|syntax|javascript|1150398|1150399|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|K|8|@]|9|@]|A|$E|F]]|$1|G|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|M|8|@]|9|@]|A|$]]]|I|$]]

<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>const log = console.log;

function* generateId() {
 for(let i = 0; ; ++i) {
 yield i;
 }
}

const idGenerator = generateId();

const ObjectWithId = new Proxy(Object, {
 construct(target, args) {
 const instance = Reflect.construct(target, args);
 instance['id'] = idGenerator.next().value;
 return instance;
 }
})

const myObject = new ObjectWithId({
 name: '@@NativeObject'
});

log(myObject.id);</code></pre>
</div>
</div>

Do JavaScript objects/variables have some sort of unique identifier? Like Ruby has <code>object_id</code>. I don't mean the DOM id attribute, but rather some sort of memory address of some kind.

JavaScript Object Id

JavaScript对象/变量是否具有某种唯一标识符？就像Ruby有object_id一样。我指的不是DOM id属性，而是某种类型的内存地址。

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