title: Create pop-up thank you message on form submit
body: <p>I just added an e-mail sign-up form to a landing page and it works fine (using firebase as back-end btw). However, I'd like to either redirect to a <strong>"thankyou.html</strong>" page or have a <strong>pop-up thank you message</strong> appear upon submit. </p>
  
  <p>How can I make it work? I know this is probably pretty easy, but I'm a novice.</p>
  
  <p>Here's the code I'm using. Included this script in html:</p>
  
  <pre><code>`&lt;script&gt;
  var signupForm = document.getElementById('signup-form');
  var signupSuccess = document.getElementById('signup-success');
  var signupError = document.getElementById('signup-error');
  var signupBtn = document.getElementById('signup-button');
  var onSignupComplete = function(error) {
    signupBtn.disabled = false;
    if (error) {
      signupError.innerHTML = 'Sorry. Could not signup.';
    } else {
      signupSuccess.innerHTML = 'Thanks for signing up!';
      // hide the form
      signupForm.style.display = 'none';
    }
  };
  function signup(formObj) {
      // Store emails to firebase
      var myFirebaseRef = new      Firebase("https://crowdfluttr.firebaseio.com/signups");
      myFirebaseRef.push({
        email: formObj.email.value,
      }, onSignupComplete);
      signupBtn.disabled = true;
      return false;
  }
  </code></pre>
  
  <p>`</p>
  
  <hr>
  
  <p>Also in Html:</p>
  
  <pre><code>&lt;div class="signup"&gt;
  &lt;p id="signup-success" class="text-success" role="alert"&gt;&lt;/p&gt;
  &lt;p id="signup-error" class="text-danger"&gt;&lt;/p&gt;
  &lt;form class="signup-form form-inline" id="signup-form" role="form" onsubmit="return signup(this)"&gt;
      &lt;input class="form-control" style="width:250px" name="email" type="email" placeholder="Your email goes here!" required&gt;
      &lt;button class="btn btn-info" id="signup-button" type="submit" &gt;Request Early Access&lt;/button&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>Any help appreciated!</p>