title: Serialize not returning value for select dropdown
body: <p>I have some code that gets a value from unselected options in a select dropdown. This displays in console.log as an array with the correct values. However, <code>serialize();</code> is not returning any values for this select when i <code>console.log(data);</code>. If I <code>console.log(boxintake);</code> this shows me the correct values being passed. </p>
  
  <p>Options are being added from button click and are working correctly. Assume all names and form names are correct.</p>
  
  <p>I would be grateful if someone could enlighten me as to why this is not working. Many thanks.</p>
  
  <p>html</p>
  
  <pre><code>&lt;div class="form-group"&gt;
      &lt;label class="labelStyle" for="box_ni"&gt;Select Your Box(es)&lt;/label&gt;&lt;br /&gt;
       &lt;select disabled id="box_ni" multiple name="box_ni[]" size="15"&gt;
        &lt;option value=""&gt;
        &lt;/option&gt;
      &lt;/select&gt;
      &lt;div id="nidstrmessage"&gt;&lt;/div&gt;
      &lt;div class="servicesHelp"&gt;&lt;lead id="serviceHelp" class="form-text text-muted help"&gt;
        Read help &lt;img src="/domain/admin/images/qmark.png" width="24px" height="24px" class="helpintk"/&gt;
        &lt;/lead&gt;
      &lt;/div&gt;
      &lt;div class="noBrtvBoxes" style="color:white;"&gt;&lt;/div&gt;
    &lt;/div&gt;
  </code></pre>
  
  <p>js</p>
  
  <pre><code>$("#USRboxni").submit(function(e) {
     e.preventDefault();
  
      var boxintake = $("#box_ni option").map(function(){
        return this.value;
       }).get();
       console.log(boxintake);
  
      var data = $("#USRboxni").serialize();
        console.log(data);
  });
  </code></pre>