title: Event listener not firing off in options.js in chrome extension
body: <p>In my options page, in my chrome extension, I want to read the user input when the user enters their value and clicks the submit button.</p>
  
  <p><strong>options.html</strong></p>
  
  <pre><code>&lt;html&gt;
  &lt;head&gt;
  
    &lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.2/jquery.min.js"&gt;&lt;/script&gt;
  
  &lt;/head&gt;
  &lt;body&gt;
  
  &lt;h1 style="font-family:Raleway;font-weight:200;text-align:center;font-size:50px;color:white;"&gt;Themes&lt;/h1&gt;
  
  &lt;input type="number" id="day" value="2" class="day"&gt;
  &lt;button id = "button1"&gt;Submit&lt;/button&gt;
  
    &lt;script src="options.js"&gt;&lt;/script&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p><strong>options.js</strong></p>
  
  <pre><code>...
  document.getElementById("button1").addEventListener("change", function(e) {
      var day = document.getElementById("day").value; // get the current value of the input field.
      alert(day);
  });
  </code></pre>