问如何获取jquery checkbox.each循环中隐藏字段的值？

EN

  <script id="reqList-template" type="text/x-handlebars-template">
     {{#resultList}}
       {{#each rsToAdd}}
           <input type="hidden" name="doc_id" class="doc_id" value="{{doc_id}}">
           <input class="checkbox" type="checkbox" name="Chk" value="{{id}}">
           <select name="type" class="type">
		<option value="1_item" th:text="#{req.parentOf}"></option>
		<option value="2_item" th:text="#{req.blocks}"></option>
		<option value="3_item" th:text="#{req.dependsOn}"></option>
		<option value="4_item" th:text="#{req.relatedTo}"></option>
	    </select>
       {{/each}}
     {{/resultList}}
  
  </script>
 
 checkbox.each(function(inex, item) {
    var selected = $(item).siblings("select").val();
    
    var commentid = $(item).siblings("input[name='doc_id']").val();   // undifined
    var commentid = $(item).siblings("input:hidden").val();    // undifined
    var commentid = $(item).find("[name=doc_id]").val();    // undifined
    
    relation_type.push({
			selected : selected
		});
 });