title: I keep getting the error firebase.database is not a function
body: <p>I'm trying to link my contact form in a portfolio website to firebase and keep getting (firebase.database is not a function) in my console</p>
  
  <p>This is for the web, using pure javascript</p>
  
  <pre><code>var firebaseConfig = {
    apiKey: "AIzaSyCzX3r8CFw84WSBuCSXR1fWM_hDrwtGMSs",
    authDomain: "portfolio-4c243.firebaseapp.com",
    databaseURL: "https://portfolio-4c243.firebaseio.com",
    projectId: "portfolio-4c243",
    storageBucket: "",
    messagingSenderId: "745737502175",
    appId: "1:745737502175:web:a26e5b0baa3769c9"
  };
  // Initialize Firebase
  firebase.initializeApp(firebaseConfig);
  
  
  var messagesRef = firebase.database().ref('messages');
  
  
  document.getElementById('contactForm').addEventListener('submit', submitForm);
  
  function submitForm(e) {
    e.preventDefault();
  
    var name = getInputVal('name');
    var email = getInputVal('email');
    var message = getInputVal('message');
  
    saveMessage(name, email, message);
  
  
  }
  
  // Function get value
  function getInputVal(id) {
    return document.getElementById(id).value;
  }
  
  //Save
  function saveMessage(name, email, message) {
    var newMessageRef = messagesRef.push();
    newMessageRef.set({
      name: name,
      email: email,
      message: message
    })
  }
  </code></pre>