blocks|key|1605169|text|如果它已经存在，则计算结果为true：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1605170|$("#yourSelect+option[value='yourValue']").length+>+0;|code-block|syntax|javascript|1605171|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|$]]

This evaluates to true if it already exists:

<pre><code>$("#yourSelect option[value='yourValue']").length &gt; 0;
</code></pre>

blocks|key|1605193|text|if+(+$("#your_select_id+option[value=<enter_value_here>]").length+==+0+){
++alert("option+doesn't+exist!");
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1605194|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 ( $("#your_select_id option[value=&lt;enter_value_here&gt;]").length == 0 ){
 alert("option doesn't exist!");
}
</code></pre>

blocks|key|1390331|text|如果不起作用，你必须这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1390332|if+(+$("#your_select_id+option[value='enter_value_here']").length+==+0+){
++alert("option+doesn't+exist!");
}|code-block|syntax|javascript|1390333|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|$]]

Does not work, you have to do this:

<pre><code>if ( $("#your_select_id option[value='enter_value_here']").length == 0 ){
 alert("option doesn't exist!");
}
</code></pre>

blocks|key|1605238|text|使用jQuery的另一种方式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1605239|var+exists+=+false;+
$('#yourSelect++option').each(function(){
++if+(this.value+==+yourValue)+{
++++exists+=+true;
++}
});|code-block|syntax|javascript|1605240|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|$]]

Another way using jQuery:

<pre><code>var exists = false; 
$('#yourSelect option').each(function(){
 if (this.value == yourValue) {
 exists = true;
 }
});
</code></pre>

blocks|key|1605303|text|var+exists+=+$("#yourSelect+option")
+++++++++++++++.filter(function+(i,+o)+{+return+o.value+===+yourValue;+})
+++++++++++++++.length+>+0;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1605304|这样做的好处是可以自动为您转义该值，这使得文本中的随机引号更容易处理。|unstyled|1605305|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 exists = $("#yourSelect option")
 .filter(function (i, o) { return o.value === yourValue; })
 .length &gt; 0;
</code></pre>

This has the advantage of automatically escaping the value for you, which makes random quotes in the text much easier to deal with.

blocks|key|1605328|text|是帮助我：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1605329|++var+key+=+'Hallo';

+++if+(+$("#chosen_b+option[value='"%2Bkey%2B"']").length+==+0+){
+++alert("option+not+exist!");

++++$('#chosen_b').append("<option+value='"%2Bkey%2B"'>"%2Bkey%2B"</option>");
++++$('#chosen_b').val(key);
+++$('#chosen_b').trigger("chosen:updated");
+++++++++++++++++++++++++}
++});|code-block|syntax|javascript|1605330|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|$]]

It's help me :

<pre><code> var key = 'Hallo';

 if ( $("#chosen_b option[value='"+key+"']").length == 0 ){
 alert("option not exist!");

 $('#chosen_b').append("&lt;option value='"+key+"'&gt;"+key+"&lt;/option&gt;");
 $('#chosen_b').val(key);
 $('#chosen_b').trigger("chosen:updated");
 }
 });
</code></pre>

blocks|key|1390490|text|我也遇到过类似的问题。我将jquery+select元素保存在一个变量中，并这样做，而不是每次都在dom中搜索select控件：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1390491|function+isValueInSelect($select,+data_value){
++++return+$($select).children('option').map(function(index,+opt){
++++++++return+opt.value;
++++}).get().includes(data_value);
}|code-block|syntax|javascript|1390492|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|$]]

I had a similar issue. Rather than run the search through the dom every time though the loop for the select control I saved the jquery select element in a variable and did this:

<pre><code>function isValueInSelect($select, data_value){
 return $($select).children('option').map(function(index, opt){
 return opt.value;
 }).get().includes(data_value);
}
</code></pre>

blocks|key|1390514|text|尽管大多数其他答案都适用于我，但我使用了.find()：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1390515|if+($("#yourSelect").find('option[value="value"]').length+===+0){
++++...
}|code-block|syntax|javascript|1390516|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|$]]

Although most of other answers worked for me I used .find():

<pre><code>if ($("#yourSelect").find('option[value="value"]').length === 0){
 ...
}
</code></pre>

How can I check whether a option already exist in select by JQuery?

I want to dynamically add options into select and so I need to check whether the option is already exist to prevent duplication.

How can I check whether a option already exist in select by JQuery

jQuery

如何检查select by JQuery中是否已经存在某个选项？我想在select中动态添加选项，因此我需要检查该选项是否已经存在，以防止重复。

问如何检查select by JQuery中是否已存在某个选项
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