Blank data comming in controller layer

Question

In HTML form trying to select size, After selecting not getting "size" data from "actionRequest", I name "namespace" but not working. if i click "Add Product" button without selecting size we get alert to select size. After using "namespace" if i click button showing size selection alert even selecting size.

This is how i displaying sizes

<div class="size-row" >
  <c:forEach items="<%= sizes %>" var="size" >
    <div class="size-col" >
      <input id="${size}" class="select-sz-rdo" type="radio" name="<portlet:namespace/>size" value="${size}"/>
      <label for="${size}" class="select-sz-rdo-lbl" >${size}</label>
    </div>
  </c:forEach>
</div>

script to show alert message

function checkSize(event) {
      var selectedSize = document.querySelector('input[name="<portlet:namespace/>size"]:checked');

      if (!selectedSize) {
        alert("Please select a size before adding to cart.");
        event.preventDefault();
      }
}

Anyone give me solution to get data from jsp to controller layer. Thank you..