title: How can I reset a paper-dropdown-menu in Polymer so nothing is selected?
body: <p>I would like to reset a Polymer paper-dropdown-menu to it's initial state in JavaScript so nothing is selected, so it looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/UrUoy.png" rel="noreferrer"><img src="https://i.stack.imgur.com/UrUoy.png" alt="paper-dropdown-menu nothing selected"></a></p>
  
  <p>I'm able to add an id to the paper-menu tag inside the paper-dropdown-menu and access it in JavaScript and choose it's selected index:</p>
  
  <pre><code>document.getElementById("accountTypeMenu").selected = 1;
  </code></pre>
  
  <p>However, I can only select an available item, so the number needs to be 0 or greater. I cannot set it to -1 to select nothing to return it to it's initial state visually, yet I can log the selected state to what I just set it to. Other values I tried to change selected to are null and undefined. </p>
  
  <p>Here is the html I'm using for the paper-dropdown-menu:</p>
  
  <pre><code>&lt;paper-dropdown-menu 
  id="accountTypeDropdown"
  selected-item="{{selectedItem}}"
  selected-item-label="{{selected}}"
  label='&amp;#65290;Account type' 
  style="width:50%;"
  noink 
  no-animations&gt;
  
      &lt;paper-menu id="accountTypeMenu"
                  class="dropdown-content"
                  onmouseup="requiredMenuFieldSelected('accountType')"&gt;
                          &lt;template is="dom-repeat"
                                    items="{{accountTypes}}"
                                    as="accountType"&gt;
                              &lt;paper-item value="[[accountType.id]]"&gt;[[accountType.name]]&lt;/paper-item&gt;
                          &lt;/template&gt;
      &lt;/paper-menu&gt;
  
  &lt;/paper-dropdown-menu&gt;
  
  &lt;input is="iron-input" 
         name="accountType" 
         type="hidden" 
         value$="[[selectedItem.value]]"&gt;
  </code></pre>