blocks|key|570946|text|几个，你可能想加入：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|570947|if("active"+in+req.body)|code-block|syntax|javascript|570948|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|$]]

A few, you probably want in:

<pre><code>if("active" in req.body)
</code></pre>

blocks|key|570994|text|您可能应该使用以下选项:+req.body.hasOwnProperty('active')|type|unstyled|depth|inlineStyleRanges|entityRanges|data|570995|它将只检查属性的存在性。|570996|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

You should probably use this instead : req.body.hasOwnProperty('active')

It will check only the very existence of the attribute.

blocks|key|571050|text|您可以使用布尔值检查，然后计算值。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|571051|item.active+=+typeof+req.body.name+===+'boolean'+&&+req.body.name|code-block|syntax|javascript|571052|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|$]]

You could use a check for boolean and then evaluate the value.

<pre><code>item.active = typeof req.body.name === 'boolean' &amp;&amp; req.body.name
</code></pre>

blocks|key|273249|text|此时，我检查node.js对象中的元素是否存在，并通过以下操作获得值：
if(req.body.name)+item.name+=+req.body.name；|type|blockquote|depth|inlineStyleRanges|entityRanges|data|273250|如果req.body.name是空字符串，这也会“失败”(输入引号，因为空名称很奇怪，但可能不是错误)。|unstyled|offset|length|style|CODE|273251|我可以想到以下几点：|273252|in：if+('name'+in+req.body)|unordered-list-item|BOLD|273253|hasOwnProperty：if+(req.body.hasOwnProperty('name')|273254|类型的：if+(typeof+req.body.name+===+'boolean')还是if+(typeof+req.body.name+!==+'undefined')|273255|然而，它们都有其优点和缺点，为了完整起见，我想指出这一点：|273256|如果有人做了类似于tyepof的事情(但在现代浏览器中可能是不可能的)，那么tyepof就会失败。|273257|如果属性存在，则hasOwnProperty失败，但它是继承的。|273258|in不需要(根据用例的不同，这可能是不需要的)|273259|entityMap^0|0|2|D|0|0|0|2|3|N|0|0|E|F|Z|0|0|3|4|13|19|15|0|0|9|6|12|6|0|8|E|0|0|2|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|13|8|@$E|14|F|15|G|H]]|9|@]|A|$]]|$1|I|3|J|5|D|7|16|8|@]|9|@]|A|$]]|$1|K|3|L|5|M|7|17|8|@$E|18|F|19|G|N]|$E|1A|F|1B|G|H]]|9|@]|A|$]]|$1|O|3|P|5|M|7|1C|8|@$E|1D|F|1E|G|N]|$E|1F|F|1G|G|H]]|9|@]|A|$]]|$1|Q|3|R|5|M|7|1H|8|@$E|1I|F|1J|G|N]|$E|1K|F|1L|G|H]|$E|1M|F|1N|G|H]]|9|@]|A|$]]|$1|S|3|T|5|D|7|1O|8|@]|9|@]|A|$]]|$1|U|3|V|5|M|7|1P|8|@$E|1Q|F|1R|G|H]|$E|1S|F|1T|G|H]]|9|@]|A|$]]|$1|W|3|X|5|M|7|1U|8|@$E|1V|F|1W|G|H]]|9|@]|A|$]]|$1|Y|3|Z|5|M|7|1X|8|@$E|1Y|F|1Z|G|H]]|9|@]|A|$]]|$1|10|3|-4|5|D|7|20|8|@]|9|@]|A|$]]]|11|$]]

<blockquote>
At this point, I check if elements in an node.js object exist and get the value by doing:
if(req.body.name) item.name = req.body.name;
</blockquote>
This will also &quot;fail&quot; if <code>req.body.name</code> is an empty string (put in quotation marks since an empty name is strange, but might not be an error).
I can think of the following:
<ul>
<li>in: <code>if ('name' in req.body)</code></li>
<li>hasOwnProperty: <code>if (req.body.hasOwnProperty('name')</code></li>
<li>typeof: Either <code>if (typeof req.body.name === 'boolean')</code> or <code>if (typeof req.body.name !== 'undefined')</code></li>
</ul>
However, all of them have advantages and disadvantages, which I want to name for the sake of completeness:
<ul>
<li><code>tyepof</code> fails if someone did something like <code>undefined = 'foo'</code> (which might not be possible in modern browsers, however)</li>
<li><code>hasOwnProperty</code> fails if the attribute exists, but was inherited</li>
<li><code>in</code> does not (which might not be desired, depending on the use case)</li>
</ul>

blocks|key|270837|text|对我来说，下面的代码工作得很好：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|270838|if+(req.body+&&+req.body.name+===+'boolean')|blockquote|270839|它将适用于所有的情况下，名称是未定义的，名称是布尔的，或名称不是布尔的，或主体不存在。它处理所有的案件。|270840|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$]]|$1|E|3|F|5|6|7|K|8|@]|9|@]|A|$]]|$1|G|3|-4|5|6|7|L|8|@]|9|@]|A|$]]]|H|$]]

For me the below code worked really well:

<blockquote>
 if (req.body &amp;&amp; typeof req.body.name === 'boolean')
</blockquote>

It will work for all the cases where name is undefined or name is boolean or name is not boolean or body does not exists. It handles all the cases.

At this point, I check if elements in an node.js object exist and get the value by doing:

<pre><code>if(req.body.name) item.name = req.body.name;
</code></pre>

However, if I want to do the same for a boolean element, it is not working.
If the passed boolean is true, no problem, but if the passed boolean is false, the if statement fails, however, I need the value of it:

<pre><code>if(req.body.active) item.active = req.body.active; // works only if true
</code></pre>

Is there a better way to check if an element in an object exists and to validate the boolean value of it?

How to check if an javascript boolean element is present

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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此时，我检查node.js对象中的元素是否存在，并通过以下操作获得值：if(req.body.name) item.name = req.body.name;但是，如果我想对布尔元素执行同样的操作，它就不能工作。如果传递的布尔值为true，则没有问题，但如果传递的布尔值为false，则If语句将失败，但是，我需要它的值...

问如何检查javascript布尔元素是否存在
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