blocks|key|1004700|text|​|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1004701|var+obj+=+{
++key1:+'value1',
++key2:+'value2',
++key3:+'value3',
++key4:+'value4'
};
var+keys+=+[];

for+(var+k+in+obj)+keys.push(k);

console.log("total+"+%2B+keys.length+%2B+"+keys:+"+%2B+keys);|code-block|syntax|javascript|1004702|1004703|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|$]]

<p><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>var obj = {
  key1: 'value1',
  key2: 'value2',
  key3: 'value3',
  key4: 'value4'
};
var keys = [];

for (var k in obj) keys.push(k);

console.log("total " + keys.length + " keys: " + keys);</code></pre>
</div>
</div>
</p>


blocks|key|1219162|text|​|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1219163|var+obj+=+{
+++key1:+'value1',
+++key2:+'value2',
+++key3:+'value3',
+++key4:+'value4'
}
var+keys+=+Object.keys(obj);
console.log('obj+contains+'+%2B+keys.length+%2B+'+keys:+'%2B++keys);|code-block|syntax|javascript|1219164|1219165|现在在大多数主流浏览器上都是supported。|offset|length|1219166|entityMap|0|LINK|mutability|MUTABLE|url|http://kangax.github.com/es5-compat-table/^0|0|0|0|E|9|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|U|8|@]|9|@]|A|$E|F]]|$1|G|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@$J|X|K|Y|1|Z]]|A|$]]|$1|L|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|M|$N|$5|O|P|Q|A|$R|S]]]]

<p><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>var obj = {
   key1: 'value1',
   key2: 'value2',
   key3: 'value3',
   key4: 'value4'
}
var keys = Object.keys(obj);
console.log('obj contains ' + keys.length + ' keys: '+  keys);</code></pre>
</div>
</div>
</p>

<p>It's <a href="http://kangax.github.com/es5-compat-table/" rel="noreferrer">supported</a> on most major browsers now.</p>


blocks|key|1219286|text|Underscore.js使转换变得非常干净：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1219287|var+keys+=+_.map(x,+function(v,+k)+{+return+k;+});|code-block|syntax|javascript|1219288|编辑:我错过了你也可以这样做：|1219289|var+keys+=+_.keys(x);|1219290|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<p>Underscore.js makes the transformation pretty clean:</p>

<pre><code>var keys = _.map(x, function(v, k) { return k; });
</code></pre>

<p>Edit: I missed that you can do this too:</p>

<pre><code>var keys = _.keys(x);
</code></pre>


blocks|key|1219211|text|如果您只需要特定于该特定对象的键，而不需要任何派生的prototype属性：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1219212|function+getKeys(obj)+{
++++var+r+=+[]
++++for+(var+k+in+obj)+{
++++++++if+(!obj.hasOwnProperty(k))+
++++++++++++continue
++++++++r.push(k)
++++}
++++return+r
}|code-block|syntax|javascript|1219213|例如：|1219214|var+keys+=+getKeys({'eggs':+null,+'spam':+true})
var+length+=+keys.length+//+access+the+`length`+property+as+usual+for+arrays|1219215|entityMap^0|Q|9|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

<p>If you only want the keys which are specific to that particular object and not any derived <code>prototype</code> properties:</p>

<pre><code>function getKeys(obj) {
    var r = []
    for (var k in obj) {
        if (!obj.hasOwnProperty(k)) 
            continue
        r.push(k)
    }
    return r
}
</code></pre>

<p>e.g:</p>

<pre><code>var keys = getKeys({'eggs': null, 'spam': true})
var length = keys.length // access the `length` property as usual for arrays
</code></pre>


blocks|key|1219137|text|var+keys+=+new+Array();
for(var+key+in+obj)
{
+++keys[keys.length]+=+key;
}

var+keyLength+=+keys.length;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1219138|要访问对象中的任意值，可以使用objkey；|unstyled|1219139|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>var keys = new Array();
for(var key in obj)
{
   keys[keys.length] = key;
}

var keyLength = keys.length;
</code></pre>

<p>to access any value from the object, you can use obj[key];</p>


blocks|key|1219245|text|obj+=+{'a':'c','b':'d'}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1219246|您可以尝试：|unstyled|1219247|[index+for+(index+in+obj)]+|1219248|这将返回：|1219249|['a','b']|1219250|获取密钥列表，或者|1219251|[obj[index]+for+(index+in+obj)]|1219252|要获取值，请执行以下操作|1219253|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|V|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$B|C]]|$1|I|3|J|5|F|7|X|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|Y|8|@]|9|@]|A|$B|C]]|$1|M|3|N|5|F|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$B|C]]|$1|Q|3|R|5|F|7|11|8|@]|9|@]|A|$]]|$1|S|3|-4|5|F|7|12|8|@]|9|@]|A|$]]]|T|$]]

<pre><code>obj = {'a':'c','b':'d'}
</code></pre>

<p>You can try: </p>

<pre><code>[index for (index in obj)] 
</code></pre>

<p>this will return:</p>

<pre><code>['a','b']
</code></pre>

<p>to get the list of keys
or </p>

<pre><code>[obj[index] for (index in obj)]
</code></pre>

<p>to get the values</p>


blocks|key|1219427|text|Anurags的答案基本上是正确的。但是要在较旧的浏览器中也支持Object.keys(obj)，您可以使用从https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys复制的以下代码。如果在浏览器中不可用，它会添加Object.keys(obj)方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1219428|if+(!Object.keys)+{
+Object.keys+=+(function()+{
+'use+strict';
+var+hasOwnProperty+=+Object.prototype.hasOwnProperty,
++++hasDontEnumBug+=+!({+toString:+null+}).propertyIsEnumerable('toString'),
++++dontEnums+=+[
++++++'toString',
++++++'toLocaleString',
++++++'valueOf',
++++++'hasOwnProperty',
++++++'isPrototypeOf',
++++++'propertyIsEnumerable',
++++++'constructor'
++++],
++++dontEnumsLength+=+dontEnums.length;

return+function(obj)+{
++if+(typeof+obj+!==+'object'+&&+(typeof+obj+!==+'function'+%7C%7C+obj+===+null))+{
++++throw+new+TypeError('Object.keys+called+on+non-object');
++}

++var+result+=+[],+prop,+i;

++for+(prop+in+obj)+{
++++if+(hasOwnProperty.call(obj,+prop))+{
++++++result.push(prop);
++++}
++}

++if+(hasDontEnumBug)+{
++++for+(i+=+0;+i+<+dontEnumsLength;+i%2B%2B)+{
++++++if+(hasOwnProperty.call(obj,+dontEnums[i]))+{
++++++++result.push(dontEnums[i]);
++++++}
++++}
++}
++return+result;
};
}());
}|code-block|syntax|javascript|1219429|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys^0|W|G|4Q|G|1J|2K|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]|$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]]|$1|K|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

<p>Anurags answer is basically correct.
But to support <code>Object.keys(obj)</code> in older browsers as well you can use the code below that is copied from 
<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys" rel="nofollow">https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys</a>
. It adds the <code>Object.keys(obj)</code> method if it's not available from the browser.</p>

<pre><code>if (!Object.keys) {
 Object.keys = (function() {
 'use strict';
 var hasOwnProperty = Object.prototype.hasOwnProperty,
    hasDontEnumBug = !({ toString: null }).propertyIsEnumerable('toString'),
    dontEnums = [
      'toString',
      'toLocaleString',
      'valueOf',
      'hasOwnProperty',
      'isPrototypeOf',
      'propertyIsEnumerable',
      'constructor'
    ],
    dontEnumsLength = dontEnums.length;

return function(obj) {
  if (typeof obj !== 'object' &amp;&amp; (typeof obj !== 'function' || obj === null)) {
    throw new TypeError('Object.keys called on non-object');
  }

  var result = [], prop, i;

  for (prop in obj) {
    if (hasOwnProperty.call(obj, prop)) {
      result.push(prop);
    }
  }

  if (hasDontEnumBug) {
    for (i = 0; i &lt; dontEnumsLength; i++) {
      if (hasOwnProperty.call(obj, dontEnums[i])) {
        result.push(dontEnums[i]);
      }
    }
  }
  return result;
};
}());
}
</code></pre>


blocks|key|1219555|text|使用Object.keys()...这就是我们要做的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1219556|以下链接的MDN站点上提供了完整的文档：|1219557|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys|1219558|entityMap|0|LINK|mutability|MUTABLE|url^0|2|D|0|0|0|2K|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|U|8|@]|D|@$9|V|A|W|1|X]]|E|$]]|$1|J|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|K|$L|$5|M|N|O|E|$P|I]]]]

<p>Use <code>Object.keys()</code>... it's the way to go.</p>

<p>Full documentation is available on the MDN site linked below:</p>

<p><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys" rel="nofollow noreferrer">https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys</a></p>


blocks|key|1004983|text|请注意，在coffeescript中，这可以在所有浏览器和节点中完成，如|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1004984|k+for+k+of+obj|code-block|syntax|javascript|1004985|因此|1004986|(1+for+_+of+obj).length|1004987|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<p>Note that in coffeescript this can be accomplished in all browsers and node as</p>

<pre><code>k for k of obj
</code></pre>

<p>and thus</p>

<pre><code>(1 for _ of obj).length
</code></pre>


blocks|key|1005092|text|支持ECMAScript+5的浏览器的递归解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1005093|var+getObjectKeys+=+function(obj)+{
++++var+keys+=+Object.keys(obj);
++++var+length+=+keys.length;

++++if+(length+!==+0)+{
++++++++for+(var+i+=+0;+i+<+length;+i%2B%2B)+{
++++++++++++if+(typeof+obj[keys[i]]+===+'object')+{
++++++++++++++++keys[keys[i]]+=+getObjectKeys(obj[keys[i]]);
++++++++++++}
++++++++}
++++}

++++return+keys;
};|code-block|syntax|javascript|1005094|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|$]]

<p>Recursive solution for browsers that support ECMAScript 5:</p>

<pre><code>var getObjectKeys = function(obj) {
    var keys = Object.keys(obj);
    var length = keys.length;

    if (length !== 0) {
        for (var i = 0; i &lt; length; i++) {
            if (typeof obj[keys[i]] === 'object') {
                keys[keys[i]] = getObjectKeys(obj[keys[i]]);
            }
        }
    }

    return keys;
};
</code></pre>


blocks|key|1219495|text|var+obj+=+{
+++key1:+'value1',
+++key2:+'value2',
+++key3:+'value3',
+++key4:+'value4'
}

console.log(Object.keys(obj));
console.log(Object.keys(obj).length)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1219496|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>var obj = {
   key1: 'value1',
   key2: 'value2',
   key3: 'value3',
   key4: 'value4'
}

console.log(Object.keys(obj));
console.log(Object.keys(obj).length)
</code></pre>


blocks|key|1005187|text|如果你决定使用Underscore.js，你最好这样做|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1005188|var+obj+=+{
++++key1:+'value1',
++++key2:+'value2',
++++key3:+'value3',
++++key4:+'value4'
}

var+keys+=+[];
_.each(+obj,+function(+val,+key+)+{
++++keys.push(key);
});
console.log(keys.lenth,+keys);|code-block|syntax|javascript|1005189|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|$]]

<p>If you decide to use Underscore.js you better do</p>

<pre class="lang-js prettyprint-override"><code>var obj = {
    key1: 'value1',
    key2: 'value2',
    key3: 'value3',
    key4: 'value4'
}

var keys = [];
_.each( obj, function( val, key ) {
    keys.push(key);
});
console.log(keys.lenth, keys);
</code></pre>


blocks|key|1219383|text|对于列出JSON对象键的逗号分隔字符串，请尝试以下操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1219384|function+listKeys(jObj){
++++var+keyString+=+'';
++++for(var+k+in+jObj){
++++++++keyString%2B=(','%2Bk);
++++}
++++return+keyString.slice(1);
}



/*+listKeys({'a'+:+'foo',+'b'+:+'foo',+'c'+:+'foo'})+->+'a,b,c'+*/|code-block|syntax|javascript|1219385|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|$]]

<p>For a comma-delineated string listing the keys of a JSON Object, try the following:</p>

<pre><code>function listKeys(jObj){
    var keyString = '';
    for(var k in jObj){
        keyString+=(','+k);
    }
    return keyString.slice(1);
}



/* listKeys({'a' : 'foo', 'b' : 'foo', 'c' : 'foo'}) -&gt; 'a,b,c' */
</code></pre>


blocks|key|1219484|text|使用ES6，您可以使用forEach遍历对象的键。要获取所有键，可以使用Object.keys，它返回对象中的所有键|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1219485|Object.keys(obj).forEach(function(keyValue,+index,+map)+{+
++console.log(keyValue);+
});|code-block|syntax|javascript|1219486|上面的代码片段的简写是，它只接受一个参数|1219487|Object.keys(obj).forEach(function(keyValue)+{+
++console.log(keyValue);+
});|1219488|entityMap^0|B|7|10|B|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

<p>Using ES6, 
you can use <code>forEach</code> to iterate over the Keys of an Object.
To get all the keys you can use <code>Object.keys</code> which returns all the keys in an Object</p>

<pre><code>Object.keys(obj).forEach(function(keyValue, index, map) { 
  console.log(keyValue); 
});
</code></pre>

<p>Short hand of the above snippet would be, which only takes one parameter</p>

<pre><code>Object.keys(obj).forEach(function(keyValue) { 
  console.log(keyValue); 
});
</code></pre>


blocks|key|1005200|text|+++++++if(props.userType){
++++++++++var+data+=+[]
++++++++++Object.keys(props.userType).map(i=>{
++++++++++++++++data.push(props.userType[i])
++++++++++})
++++++++++setService(data)
++++++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1005201|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>       if(props.userType){
          var data = []
          Object.keys(props.userType).map(i=&gt;{
                data.push(props.userType[i])
          })
          setService(data)
        }
</code></pre>


blocks|key|1219618|text|现代浏览器确实支持：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1219619|​|1219620|var+obj+=+{
+++key1:+'value1',
+++key2:+'value2',
+++key3:+'value3',
+++key4:+'value4'
}
console.log(Object.keys(obj));
//+we+can+also+get+values
console.log(Object.values(obj));|code-block|syntax|javascript|1219621|1219622|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|N|8|@]|9|@]|A|$G|H]]|$1|I|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|P|8|@]|9|@]|A|$]]]|K|$]]

<p>Modern browsers do support:</p>
<p><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>var obj = {
   key1: 'value1',
   key2: 'value2',
   key3: 'value3',
   key4: 'value4'
}
console.log(Object.keys(obj));
// we can also get values
console.log(Object.values(obj));</code></pre>
</div>
</div>
</p>


blocks|key|1219358|text|使用slice、apply和join方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1219359|var+print+=+Array.prototype.slice.apply(+obj+);
alert('length='%2Bprint.length%2B'+list'%2Bprint.join());|code-block|syntax|javascript|1219360|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|$]]

<p>using slice, apply and join method.</p>

<pre><code>var print = Array.prototype.slice.apply( obj );
alert('length='+print.length+' list'+print.join());
</code></pre>


<p>I have a JavaScript object like</p>

<pre><code>var obj = {
   key1: 'value1',
   key2: 'value2',
   key3: 'value3',
   key4: 'value4'
}
</code></pre>

<p>How can I get the length and list of keys in this object?</p>


Getting JavaScript object key list

我有一个JavaScript对象，比如var obj = {   key1: 'value1',   key2: 'value2',   key3: 'value3',   key4: 'value4'}如何获取此对象中键的长度和列表？

问获取JavaScript对象键列表
EN

回答 17

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问获取JavaScript对象键列表EN

回答 17

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问获取JavaScript对象键列表
EN