blocks|key|1624243|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1624244|var+keys+=+[];
for+(var+key+in+dictionary)+{
++if+(dictionary.hasOwnProperty(key))+{
++++keys.push(key);
++}
}|code-block|syntax|javascript|1624245|之所以需要hasOwnProperty，是因为可以将键插入到dictionary的原型对象中。但您通常不希望将这些键包含在列表中。|offset|length|style|CODE|1624246|例如，如果您这样做：|1624247|Object.prototype.c+=+3;
var+dictionary+=+{a:+1,+b:+2};|1624248|然后在dictionary上执行for...in循环，你会得到a和b，但你也会得到c。|1624249|entityMap^0|0|0|5|E|U|A|0|0|0|3|A|G|8|V|1|X|1|15|1|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]|$I|Z|J|10|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|11|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|12|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|13|8|@$I|14|J|15|K|L]|$I|16|J|17|K|L]|$I|18|J|19|K|L]|$I|1A|J|1B|K|L]|$I|1C|J|1D|K|L]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|T|$]]

Try this:

<pre><code>var keys = [];
for (var key in dictionary) {
 if (dictionary.hasOwnProperty(key)) {
 keys.push(key);
 }
}
</code></pre>

<code>hasOwnProperty</code> is needed because it's possible to insert keys into the prototype object of <code>dictionary</code>. But you typically don't want those keys included in your list.

For example, if you do this:

<pre><code>Object.prototype.c = 3;
var dictionary = {a: 1, b: 2};
</code></pre>

and then do a <code>for...in</code> loop over <code>dictionary</code>, you'll get <code>a</code> and <code>b</code>, but you'll also get <code>c</code>.

blocks|key|1409568|text|for+(var+key+in+dictionary)+{
++//+Do+something+with+key
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1409569|是for..in+statement。|unstyled|offset|length|1409570|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Statements/for...in^0|0|1|H|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@$G|S|H|T|1|U]]|A|$]]|$1|I|3|-4|5|F|7|V|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|P]]]]

<pre><code>for (var key in dictionary) {
 // Do something with key
}
</code></pre>
It's the <a href="https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Statements/for...in" rel="nofollow noreferrer">for..in statement</a>.

blocks|key|1624436|text|只有一个简短的说明。如果您使用库(jQuery、Prototype等)，请谨慎使用for..in，因为它们中的大多数都会向创建的对象(包括字典)添加方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1624437|这意味着当你遍历它们时，方法名将以键的形式出现。如果您使用的是库，请查看文档并查找可枚举部分，在那里您将找到用于对象迭代的正确方法。|1624438|entityMap|0|LINK|mutability|MUTABLE|url|https://en.wikipedia.org/wiki/JQuery|1|https://en.wikipedia.org/wiki/Prototype_JavaScript_Framework^0|15|7|H|6|0|O|9|1|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@$9|U|A|V|1|W]|$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|G|5|6|7|10|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]|P|$5|K|L|M|E|$N|Q]]]]

Just a quick note. Be wary of using <code>for..in</code> if you use a library (<a href="https://en.wikipedia.org/wiki/JQuery" rel="nofollow noreferrer">jQuery</a>, <a href="https://en.wikipedia.org/wiki/Prototype_JavaScript_Framework" rel="nofollow noreferrer">Prototype</a>, etc.), as most of them add methods to created Objects (including dictionaries).
This will mean that when you loop over them, method names will appear as keys. If you are using a library, look at the documentation and look for an enumerable section, where you will find the right methods for iteration of your objects.

blocks|key|1624480|text|简单的jQuery方式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1624481|这是我使用的：|1624482|DictionaryObj是您要遍历的JavaScript字典对象。和值，关键字当然是它们在字典中的名称。|1624483|$.each(DictionaryObj,+function+(key,+value)+{
++++$("#storeDuplicationList")
++++++++.append($("<li></li>")
++++++++.attr("value",+key)
++++++++.text(value));
});|code-block|syntax|javascript|1624484|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Simple jQuery way:
This is what I use:
DictionaryObj being the JavaScript dictionary object you want to go through. And value, key of course being the names of them in the dictionary.
<pre><code>$.each(DictionaryObj, function (key, value) {
 $(&quot;#storeDuplicationList&quot;)
 .append($(&quot;&lt;li&gt;&lt;/li&gt;&quot;)
 .attr(&quot;value&quot;, key)
 .text(value));
});
</code></pre>

I have an associative array in JavaScript:
<pre><code>var dictionary = {
 &quot;cats&quot;: [1,2,3,4,5],
 &quot;dogs&quot;: [6,7,8,9,10]
};
</code></pre>
How do I get this dictionary's keys? I.e., I want
<pre><code>var keys = [&quot;cats&quot;, &quot;dogs&quot;];
</code></pre>
<hr />
Just to get the terminology correct - there is no such thing as an 'associative array' in JavaScript - this is technically just an <code>object</code> and it is the object keys we want.

Getting a list of associative array keys

jQuery

我在JavaScript中有一个关联数组：var dictionary = {    "cats": [1,2,3,4,5],    "dogs": [6,7,8,9,10]};我怎样才能得到这本字典的钥匙呢？也就是说，我想var keys = ["cats", "dogs"];只是为了纠正术语- JavaScript...

问获取关联数组键的列表
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