title: How to call a function when Polymer paper-input is submitted?
body: <p>I've got a polymer app that takes a text input (ID) and returns a "yes" or "no" based on whether the ID is in a list or not. Ideally, a user can press enter or click a "lookup" button, and the "search for ID" function will get called. </p>
  
  <p>Can I do this without using a form?
  If I use a form, can I do this without making a post/put/get request? The data is all stored in a property (array) of the element. </p>
  
  <pre><code>&lt;dom-module id="demo-app"&gt;
    &lt;template&gt;
      &lt;style&gt;
        :host {
          display: block;
        }
      &lt;/style&gt;
      &lt;paper-card heading="Search for ID"&gt;
        &lt;div class="card-content"&gt;
          &lt;paper-input id="input" always-float-label label="ID"&lt;/paper-input&gt;
        &lt;/div&gt;
      &lt;/paper-card&gt;
    &lt;/template&gt;
  
    &lt;script&gt;
      Polymer({
  
        is: 'demo-app',
  
        properties: {
          myIds: {
            type: Array,
            value: ['testID1', 'testID2'],
          },
          inputObj: {
            type: Object,
            value: function(){
              return this.$.input;
            }
          },
          userInput: {
            type: String,
          },
        },
        onEnter: function(){
          if(this.myIds.includes(this.userInput)) {
            console.log(this.userInput);
          }
        },
  
      });
    &lt;/script&gt;
  &lt;/dom-module&gt;
  </code></pre>