Кнопки +/- на формах

form.html

<div class="input-group input-group">
  <div class="input-group-prepend">
    <button class="btn btn-secondary js-num" type="button" data-type="minus" data-field="input-one">&minus;</button>
  </div>
  <input type="text" min="0" max="100" step="5" value="1" id="input-one" class="form-control">
  <div class="input-group-append">
    <button class="btn btn-secondary js-num" type="button" data-type="plus" data-field="input-one">+</button>
  </div>
</div>

js-num.js

$('.js-num').on('click', (function() {
  var type = $(this).attr('data-type');
  var field = $(this).attr('data-field');
  // var input = $('input[name ='+ field +']');
  var input = $('input#' + field);
  var min = input.attr('min');
  var max = input.attr('max');
  var step = input.attr('step');

  min =parseInt(min);
  max =parseInt(max);
  step =parseInt(step);
  var value = input.val();
  var currentVal = value;

  if(type == 'minus')
  {
    if(value>min)
    {
      currentVal = parseInt(value) - step;
      input.val(currentVal).change();
    }
  }
  if(type == 'plus')
  {
    if(value<max)
    {
      currentVal = parseInt(value) + step;
      input.val(currentVal).change();
    }
  }
  $('input#' + field).val(currentVal);
}));