Is it possible create a multi-step form?

Hi, my question is if it is possible to create a multi-step form with framework7.
For example , I have 3 step

html code:

 <div data-name="regForm" class="page">	
<div class="page-content pg-no-padding">

	<div class="row justify-content-center">
		<div class="col-100 tablet-100 desktop-80">
			<div class="block">
			<form id="regForm" action="">


				<!-- One "tab" for each step in the form: -->
				<div class="tab">Name:
				  <p><input placeholder="First name..." oninput="this.className = ''"></p>
				  <p><input placeholder="Last name..." oninput="this.className = ''"></p>

				<div class="tab">Contact Info:
				  <p><input placeholder="E-mail..." oninput="this.className = ''"></p>
				  <p><input placeholder="Phone..." oninput="this.className = ''"></p>

				<div class="tab">Birthday:
				  <p><input placeholder="dd" oninput="this.className = ''"></p>
				  <p><input placeholder="mm" oninput="this.className = ''"></p>
				  <p><input placeholder="yyyy" oninput="this.className = ''"></p>

				<div class="tab">Login Info:
				  <p><input placeholder="Username..." oninput="this.className = ''"></p>
				  <p><input placeholder="Password..." oninput="this.className = ''"></p>

				<div style="overflow:auto;">
				  <div style="float:right;">
				    <button type="button" id="prevBtn" onclick="nextPrev(-1)">Previous</button>
				    <button type="button" id="nextBtn" onclick="nextPrev(1)">Next</button>

				<!-- Circles which indicates the steps of the form: -->
				<div style="text-align:center;margin-top:40px;">
				  <span class="step"></span>
				  <span class="step"></span>
				  <span class="step"></span>
				  <span class="step"></span>


</div> <!-- ./ page-content-->

and this is the js code included in index.html page

  // show the name
  var currentTab = 0; // Current tab is set to be the first tab (0)
  showTab(currentTab); // Display the current tab

 function showTab(n) {
  // This function will display the specified tab of the form ...
  var x = document.getElementsByClassName("tab");
  x[n].style.display = "block";
  // ... and fix the Previous/Next buttons:
  if (n == 0) {
     document.getElementById("prevBtn").style.display = "none";
 } else {
     document.getElementById("prevBtn").style.display = "inline";
  if (n == (x.length - 1)) {
     document.getElementById("nextBtn").innerHTML = "Submit";
 } else {
     document.getElementById("nextBtn").innerHTML = "Next";
  // ... and run a function that displays the correct step indicator:

function nextPrev(n) {

  // This function will figure out which tab to display
  var x = document.getElementsByClassName("tab");
  // Exit the function if any field in the current tab is invalid:
  if (n == 1) return false;
  // Hide the current tab:
  x[currentTab].style.display = "none";
  // Increase or decrease the current tab by 1:
  currentTab = currentTab + n;
  // if you have reached the end of the form... :
  if (currentTab >= x.length) {
  //...the form gets submitted:
  return false;
  // Otherwise, display the correct tab:
  function validateForm() {
  // This function deals with validation of the form fields
  var x, y, i, valid = true;
  x = document.getElementsByClassName("tab");
  y = x[currentTab].getElementsByTagName("input");
  // A loop that checks every input field in the current tab:
  for (i = 0; i < y.length; i++) {
  // If a field is empty...
  if (y[i].value == "") {
  // add an "invalid" class to the field:
  y[i].className += " invalid";
  // and set the current valid status to false:
  valid = false;
  // If the valid status is true, mark the step as finished and valid:
  if (valid) {
  document.getElementsByClassName("step")[currentTab].className += " finish";
  return valid; // return the valid status
  function fixStepIndicator(n) {
  // This function removes the "active" class of all steps...
  var i, x = document.getElementsByClassName("step");
  for (i = 0; i < x.length; i++) {
  x[i].className = x[i].className.replace(" active", "");
  //... and adds the "active" class to the current step:
  x[n].className += " active";

but it doesn’t work with framework7. It said me:

  x[n].style.display = "block";
  Uncaught TypeError: Cannot read property 'style' of undefined

Thank you in advance

That has something to do with your code, it is good habit to declare and use the stackPages: trueproperty at the app object creation in cases where you consider using a multi-step form… It keeps pages in DOM…