title: Show and hide an iframe with condition
body: <p>I have a one page homepage with below structure. In the portfolio section i have embeded a paypal button. I am planing to use the auto return function of paypal where buyers are brought back to my page upon payment completion. And in the Contact section i have embeded an iframe which is a survey made with google docs. I want to show this only buyers who completed purchase. How can i do this?</p>
  
  <pre><code>&lt;!DOCTYPE HTML&gt;
  &lt;html&gt;
  &lt;head&gt;
      &lt;title&gt;Mini&lt;/title&gt;     
  &lt;/head&gt;
  &lt;body&gt;
  
      &lt;!-- Nav --&gt;
          &lt;nav id="nav"&gt;
              &lt;ul class="container"&gt;
                  &lt;li&gt;&lt;a href="#top"&gt;&lt;/a&gt;&lt;/li&gt;
                  &lt;li&gt;&lt;a href="#work"&gt;&lt;/a&gt;&lt;/li&gt;
                  &lt;li&gt;&lt;a href="#portfolio"&gt;&lt;/a&gt;&lt;/li&gt;
                  &lt;li&gt;&lt;a href="#contact"&gt;&lt;/a&gt;&lt;/li&gt;
              &lt;/ul&gt;
          &lt;/nav&gt;
  
      &lt;!-- Home --&gt;
          &lt;div class="wrapper style1 first"&gt;
              &lt;article class="container" id="top"&gt;
                      &lt;div&gt;
                      &lt;/div&gt;                  
              &lt;/article&gt;
          &lt;/div&gt;
  
      &lt;!-- Work --&gt;
          &lt;div class="wrapper style2"&gt;
              &lt;article id="work"&gt;                 
                  &lt;div class="container"&gt;
                      &lt;div class="row"&gt;
                      &lt;/div&gt;
                  &lt;/div&gt;  
              &lt;/article&gt;
          &lt;/div&gt;
  
      &lt;!-- Portfolio --&gt;
          &lt;div class="wrapper style3"&gt;
              &lt;article id="portfolio"&gt;                    
                  &lt;form action="https://www.paypal.com/cgi-bin/webscr" method="post" target="_top"&gt;
                  //Here is the paypal button
                  &lt;/form&gt;
              &lt;/article&gt;
          &lt;/div&gt;
  
      &lt;!-- Contact --&gt;
          &lt;div class="wrapper style4"&gt;
              &lt;article id="contact" class="container 75%"&gt;                    
                      &lt;div class="row"&gt;
                          //below the survey made with google docs
                          &lt;iframe src="https://docs.google.com/forms/...&lt;/iframe&gt;
                      &lt;/div&gt;
  
              &lt;/article&gt;
          &lt;/div&gt;
  
      &lt;!-- Scripts --&gt;
  &lt;/body&gt;
  </code></pre>
  
  <p></p>