title: Cannot link my extension's popup(html file) and javascript file using onclick()
body: <p>I cannot link my extension's HTML file with JS.The output I was expecting was that h4 line would change into &quot;not skipper&quot;.
  I have been trying <code>onclick</code> function, I read that I needed to use <code>.addEventListener()</code> but I couldn't make it work.</p>
  <p>The webpage works when I test it as an actual webpage using live server but fails when i try to use it in an extension.</p>
  <p>I wanted to know how to correct my <code>onclick()</code> mistake and how to use <code>.addEventListener()</code> for this code
  Manifest.json file</p>
  <pre><code>{
  &quot;manifest_version&quot;: 2,
  &quot;name&quot;: &quot;Skipper&quot;,
  &quot;version&quot;: &quot;1.0&quot;,
  
  
  &quot;description&quot;: &quot;Does something&quot;,
  &quot;browser_action&quot;: {
    &quot;default_icon&quot;: &quot;stuff/potato.jpg&quot;,
    &quot;default_popup&quot;: &quot;popup.html&quot;,
    &quot;default_title&quot;: &quot;Skipper!&quot;
  },
  &quot;icons&quot;: {
    &quot;48&quot;: &quot;stuff/potato.jpg&quot;
  },
  &quot;permissions&quot;: [
    &quot;activeTab&quot;
   ],
  
  
  &quot;content_scripts&quot;: [
    {
      &quot;matches&quot;: [&quot;&quot;http://*/*&quot;,&quot;https://*/*&quot;],
      &quot;js&quot;: [&quot;pop.js&quot;]
    }
    ]
  
  
   }
  </code></pre>
  <p>This is my extension's HTML which is in proper directory</p>
  <pre><code>&lt;html lang=&quot;en&quot;&gt;
  &lt;head&gt;
  &lt;meta charset=&quot;UTF-8&quot;&gt;
  &lt;meta http-equiv=&quot;X-UA-Compatible&quot; content=&quot;IE=edge&quot;&gt;
  &lt;meta name=&quot;viewport&quot; content=&quot;width=device-width, initial-scale=1.0&quot;&gt;
  &lt;title&gt;Skipper&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;h4 id=&quot;help&quot;&gt;Skipper&lt;/h4&gt;
      &lt;button onclick=&quot;func()&quot;&gt;Reload&lt;/button&gt;
  &lt;/body&gt;
  &lt;script src=&quot;pop.js&quot;&gt;&lt;/script&gt;
  &lt;/html&gt;
  </code></pre>
  <p>This is my JS file</p>
  <pre><code>function func()
  {
      var change=document.getElementById(&quot;line&quot;).innerHTML=&quot;not skipper&quot;;
      return change;
  }
  </code></pre>