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document.addEventListener("DOMContentLoaded", function() {

  new FancyForm({
    renderTo: 'container',
    title: 'Tabs',
    width: 285,
    height: 300,
    activeTab: 0,
    url: 'submit.php',
    tabs: ['First', 'Second', 'Third'],
    items: [{
      type: 'tab',
      items: [{
        type: 'string',
        label: 'Name',
        emptyText: 'Name',
        name: 'name'
      }, {
        type: 'string',
        label: 'SurName',
        emptyText: 'SurName',
        name: 'surname'
      }, {
        type: 'password',
        label: 'Pass',
        emptyText: 'Pass',
        name: 'pass'
      }]
    }, {
      type: 'tab',
      items: [{
        type: 'number',
        label: 'Age',
        name: 'age',
        min: 20,
        max: 100
      }, {
        type: 'checkbox',
        label: 'Married',
        name: 'married'
      }]
    }, {
      type: 'tab',
      items: [{
        type: 'combo',
        label: 'Country',
        name: 'country',
        data: [{
          index: 0,
          country: 'USA'
        }, {
          index: 1,
          country: 'Canada'
        }],
        displayKey: 'country',
        valueKey: 'index',
        value: 0
      }, {
        type: 'textarea',
        inputWidth: 250,
        height: 110,
        emptyText: 'About',
        label: false,
        name: 'about'
      }]
    }]
  });

});

<script src="https://cdn.fancygrid.com/fancy.min.js"></script>

<div id="container"></div>