blocks|key|1189448|text|$("#mydropdown+option").length|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1189449|或者如果你已经有了参考资料，|unstyled|1189450|$(myDropdown).find("option").length|1189451|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>$("#mydropdown option").length
</code></pre>

Or if you already got a reference to it,

<pre><code>$(myDropdown).find("option").length
</code></pre>

blocks|key|1189524|text|使用length+property或the+size+method找出jQuery集合中有多少项。使用descendant+selector选择<select>中的所有<option>。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1189525|HTML：|1189526|<select+id="myDropDown">
<option>1</option>
<option>2</option>
.
.
.
</select>|code-block|syntax|javascript|1189527|JQuery：|1189528|var+numberOfOptions+=+$('select#myDropDown+option').length|1189529|快速说明一下，通常您需要在jquery中为一个非常具体的东西做一些事情，但您首先需要查看这个非常具体的东西是否存在。length属性是一个完美的工具。示例：|1189530|+++if($('#myDropDown+option').length+>+0{
++++++//do+your+stuff..
++++}+|1189531|这“翻译”为“如果带有ID=myDropDown的项目有任何后代”选项，去做你需要做的事情。|1189532|entityMap|0|LINK|mutability|MUTABLE|url|http://api.jquery.com/length/|1|http://api.jquery.com/size/|2|http://api.jquery.com/descendant-selector/^0|20|8|2C|8|2|F|0|I|F|1|1F|J|2|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]]|D|@$9|1D|A|1E|1|1F]|$9|1G|A|1H|1|1I]|$9|1J|A|1K|1|1L]]|E|$]]|$1|F|3|G|5|6|7|1M|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1N|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1O|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|1P|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1Q|8|@]|D|@]|E|$]]|$1|S|3|T|5|J|7|1R|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1S|8|@]|D|@]|E|$]]|$1|W|3|-4|5|6|7|1T|8|@]|D|@]|E|$]]]|X|$Y|$5|Z|10|11|E|$12|13]]|14|$5|Z|10|11|E|$12|15]]|16|$5|Z|10|11|E|$12|17]]]]

Use the <a href="http://api.jquery.com/length/" rel="nofollow noreferrer">length property</a> or <a href="http://api.jquery.com/size/" rel="nofollow noreferrer">the size method</a> to find out how many items are in a jQuery collection. Use the <a href="http://api.jquery.com/descendant-selector/" rel="nofollow noreferrer">descendant selector</a> to select all <code>&lt;option&gt;</code>'s within a <code>&lt;select&gt;</code>.

HTML:

<pre><code>&lt;select id="myDropDown"&gt;
&lt;option&gt;1&lt;/option&gt;
&lt;option&gt;2&lt;/option&gt;
.
.
.
&lt;/select&gt;
</code></pre>

JQuery:

<pre><code>var numberOfOptions = $('select#myDropDown option').length
</code></pre>

And a quick note, often you will need to do something in jquery for a very specific thing, but you first need to see if the very specific thing exists. The length property is the perfect tool.
example:

<pre><code> if($('#myDropDown option').length &gt; 0{
 //do your stuff..
 } 
</code></pre>

This 'translates' to "If item with ID=myDropDown has any descendent 'option' s, go do what you need to do.

blocks|key|1189599|text|获取特定选择元素中的选项数量|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1189600|$("#elementid+option").length|code-block|syntax|javascript|1189601|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|$]]

Get the number of options in a particular select element

<pre><code>$("#elementid option").length
</code></pre>

blocks|key|975387|text|Click+here+to+see+a+previous+post+about+this|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|975388|基本上只针对select的ID并执行以下操作：|975389|var+numberOfOptions+=+$('#selectId+option').length;|code-block|syntax|javascript|975390|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/1152738/counting-the-number-of-options-tag-in-the-select-dom-element-in-jquery^0|0|18|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|C|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

<a href="https://stackoverflow.com/questions/1152738/counting-the-number-of-options-tag-in-the-select-dom-element-in-jquery">Click here to see a previous post about this</a>

Basically just target the ID of the select and do this:

<pre><code>var numberOfOptions = $('#selectId option').length;
</code></pre>

blocks|key|975206|text|$('#idofdropdown+option').length;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|975207|这应该就行了。|unstyled|975208|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>$('#idofdropdown option').length;
</code></pre>

That should do it.

blocks|key|1189382|text|alert($('#select_id+option').length);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1189383|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>alert($('#select_id option').length);
</code></pre>

blocks|key|1189455|text|$('#dropdown_id').find('option').length|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1189456|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>$('#dropdown_id').find('option').length
</code></pre>

blocks|key|1189551|text|$('select+option').length;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1189552|或|unstyled|1189553|$("select+option").size()|1189554|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>$('select option').length;
</code></pre>

or

<pre><code>$("select option").size()
</code></pre>

blocks|key|975417|text|在纯javascript中，你可以直接调用选择框id的长度。它会更快。通常，本机javascript在现代浏览器中的性能越来越好。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|975418|这可以在javascript中通过以下方式实现：|975419|+++++var+dropdownFilterSite+=+document.querySelector(+'#dropDownId'+);++//Similar+to+jQuery

var+length+=+dropdownFilterSite.length.|code-block|syntax|javascript|975420|一个很好的学习网站|975421|www.youmightnotneedjquery.com|975422|Todd+Motto的一段值得观看的好视频|975423|https://www.youtube.com/watch?v=pLISnANteJY|offset|length|975424|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|0|0|0|0|17|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|10|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|11|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|12|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|13|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|14|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|15|8|@]|9|@$Q|16|R|17|1|18]]|A|$]]|$1|S|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|P]]]]

With pure javascript you can just call the length on the id of the select box. 
It will be more faster. 
Typically with everything native javascript is performing better and better with modern browsers 

This can be achieved in javascript by 

<pre><code> var dropdownFilterSite = document.querySelector( '#dropDownId' ); //Similar to jQuery

var length = dropdownFilterSite.length.
</code></pre>

Good website for some learning 

www.youmightnotneedjquery.com

A good video to watch by Todd Motto 

<a href="https://www.youtube.com/watch?v=pLISnANteJY" rel="nofollow">https://www.youtube.com/watch?v=pLISnANteJY</a>

How do I check, using jQuery, how many options are there in a drop down menu?

Thanks.

How do I check how many options there are in a dropdown menu?

jQuery

如何使用jQuery检查下拉菜单中有多少个选项？谢谢。

问如何检查下拉菜单中有多少个选项？
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问如何检查下拉菜单中有多少个选项？EN

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问如何检查下拉菜单中有多少个选项？
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