product form with radio button variants

<form action="/cart/add" method="post">
	{% if product.variants.size > 1 %}
		{% for variant in product.variants %}
      <input type="radio" id="variant-{{ variant.title | handle }}" name="variant" value="{{ variant.id }}" />
      <label for="variant-{{ variant.title | handle }}">{{ variant.title }}</label>
      <br />
		{% endfor %}
  {% endif %}

	<input type="hidden" name="id" class="product-select" value="{{ product.variants[0].id }}" />
	<label for="quantity">Quantity</label>
	<input type="text" name="quantity" id="quantity" value="1" />
	<button type="submit">Add to cart</button>
</form>

$('input').click(function() {
  var variantID = $(this).val();
  $('.product-select').val(variantID);
});