Pagination in JavaScript/jQuery in table

var selectedRow = null

function onFormSubmit() {
  if (validate()) {
    var formData = readFormData();

    if (selectedRow == null)
      insertNewRecord(formData);
    else
      updateRecord(formData);

    resetForm();
  }
}

function readFormData() {
  var formData = {};
  formData["fullName"] = document.getElementById("fullName").value;
  formData["age"] = document.getElementById("age").value;
  formData["mobile"] = document.getElementById("mobile").value;
  formData["city"] = document.getElementById("city").value;
  return formData;
}

function insertNewRecord(data) {
  var table = document.getElementById("data").getElementsByTagName('tbody')[0];
  var newRow = table.insertRow(table.length);
  var cell1 = newRow.insertCell(0);
  cell1.innerHTML = data.fullName;
  var cell2 = newRow.insertCell(1);
  cell2.innerHTML = data.age;
  var cell3 = newRow.insertCell(2);
  cell3.innerHTML = data.mobile;
  var cell4 = newRow.insertCell(3);
  cell4.innerHTML = data.city;
}

<form onsubmit="event.preventDefault();onFormSubmit();" autocomplete="off">
  <input type="text" name="fullName" id="fullName" placeholder="Enter Full Name">
  <label class="validation-error hide" id="fullNameValidationError">This field is required.</label>
  <input type="text" name="age" id="age" placeholder="Enter Age">
  <input type="text" name="mobile" id="mobile" placeholder="Enter Phone Number">
  <input type="text" name="city" id="city" placeholder="Enter Current City">
  <input type="submit" value="Submit">
  <table class="list" id="data">
    <thead>
      <tr>
        <th>Full Name <button onclick="sortTable(0)">sort</button></th>
        <th>Age <button onclick="sortTable(1)">sort</button></th>
        <th>Phone Number <button onclick="sortTable(2)">sort</button></th>
        <th>City <button onclick="sortTable(3)">sort</button></th>
      </tr>
    </thead>
    <tbody id="table-body"></tbody>
  </table>
</form>