document.addEventListener('DOMContentLoaded', function () {
    const storeSelect = document.getElementById('storeSelect');
    const breadcrumbStore = document.getElementById('breadcrumbStore');

    const cuTable = document.getElementById('cuTable');
    const gsTable = document.getElementById('gsTable');
    const comboTable = document.getElementById('comboTable');

    showOnlyTable('cu'); // 초기 세팅

    storeSelect.addEventListener('change', function () {
        const selected = this.value;
        showOnlyTable(selected);
    });

    function showOnlyTable(store) {
        cuTable.style.display = 'none';
        gsTable.style.display = 'none';
        comboTable.style.display = 'none';

        if (store === 'cu') {
            cuTable.style.display = ''; // 빈 문자열로 설정해서 기본 상태로 복귀
            breadcrumbStore.textContent = 'CU 상품';
        } else if (store === 'gs') {
            gsTable.style.display = '';
            breadcrumbStore.textContent = 'GS 상품';
        } else if (store === 'combo') {
            comboTable.style.display = '';
            breadcrumbStore.textContent = '콤보 상품';
        }
    }
});

manageAdiminProduct.jsp

<%@ page contentType="text/html; charset=UTF-8" %>
<!DOCTYPE html>
<html lang="ko">
<head>
  <meta charset="UTF-8">
  <title>Product Page</title>

  <!-- CSS 절대경로 -->
  <link href="${pageContext.request.contextPath}/admin/assets/css/bootstrap.css" rel="stylesheet">
  <link href="${pageContext.request.contextPath}/admin/assets/css/font-awesome.css" rel="stylesheet">
  <link href="${pageContext.request.contextPath}/admin/assets/css/custom-styles.css" rel="stylesheet">
  <link href="assets/css/dropdown.css" rel="stylesheet" />
</head>

<body>

<div id="wrapper">

<!-- 네비게이션바 -->
		<nav class="navbar navbar-default top-navbar" role="navigation">
			<div class="navbar-header">
			<!-- 화면 상단의 메뉴 버튼 요소 -->
				<button type="button" class="navbar-toggle waves-effect waves-dark"
					data-toggle="collapse" data-target=".sidebar-collapse">
					<span class="sr-only">Toggle navigation</span> <span
						class="icon-bar"></span> <span class="icon-bar"></span> <span
						class="icon-bar"></span>
				</button>

				<a class="navbar-brand waves-effect waves-dark"
					href="/admin/manageMember"> <i class="large material-icons"></i>
					<strong>HoneyComboFactory</strong>
				</a>

				
			</div>
			<!-- 사이드바 드롭다운 -->
			<ul class="nav navbar-top-links navbar-right">
				<li><a class="dropdown-button waves-effect waves-dark" href="#"
					data-activates="dropdown1"><i class="fab fa-user fa-fw"></i><b>${memberVO.memberName}
					<!--  로그인한 회원 이름 출력 -->
						</b><i class="material-icons right">arrow_drop_down</i></a></li>
			</ul>
		</nav>
		
<nav class="navbar-default navbar-side" role="navigation">
			<div class="sidebar-collapse">
				<ul class="nav" id="main-menu">
				<!-- 1. 회원관리 -->
					<li><a class="active-menu waves-effect waves-dark"
						href="/admin/manageMember">회원관리</a></li>
				<!-- 2. 상품관리 (드롭다운 포함) -->	
					<li class="dropdown"><a href="/admin/product/combo" class="dropdown-toggle">상품관리</a>
					<!-- 꿀조합 상품을 기본으로 함 -->
						<ul class="dropdown-menu">
							<li><a href="/admin/product/cu">CU상품</a></li>
							<li><a href="/admin/product/gs">GS상품</a></li>
							<li><a href="/admin/product/combo">꿀조합</a></li>
						</ul></li>
				<!-- 3. 게시판 관리 (드롭다운 포함) -->	
					<li class="dropdown"><a href="/admin/board/boardCombo" class="dropdown-toggle">게시판
							관리</a>
						<ul class="dropdown-menu">
							<li><a href="/admin/board/boardCombo">꿀조합</a></li>
							<li><a href="/admin/board/faq">FAQ</a></li>
						</ul></li class="logout-menu"> <!-- css 적용 위해 클래스 추가 -->
				<!-- 4. 로그아웃 -->
					<li><a href="/client/main" class="waves-effect waves-dark"></i>로그아웃</a></li>
				</ul>
			</div>
		</nav>

  <div id="page-wrapper">
    <div class="header">
      <h1 class="page-header">Product Page</h1>
      <ol class="breadcrumb">
        <li><a href="#">Home</a></li>
        <li><a href="#">상품관리</a></li>
        <li class="active" id="breadcrumbStore">CU 상품</li>
      </ol>
    </div>

    <div id="page-inner">

      <div class="row">
        <div class="col-md-12">
          <div class="card">
            <div class="card-action">
              상품관리
            </div>
            <div class="card-content">
              <div class="table-responsive">

                <!-- 드롭다운 -->
                <div style="margin-bottom: 20px;">
                  <select id="storeSelect" class="form-control" style="width: 200px;">
                    <option value="cu" selected>CU 상품</option>
                    <option value="gs">GS 상품</option>
                    <option value="combo">콤보 상품</option>
                  </select>
                </div>

                <!-- CU 테이블 -->
                <table class="table table-striped table-bordered table-hover" id="cuTable">
                  <thead>
                    <tr>
                      <th>상품번호</th><th>상품명</th><th>가격</th><th>할인율</th><th>할인가격</th><th>재고</th>
                    </tr>
                  </thead>
                  <tbody>
                    <tr><td>1001</td><td>CU 컵밥</td><td>4500원</td><td>10%</td><td>4050원</td><td>30개</td></tr>
                    <tr><td>1002</td><td>CU 삼각김밥</td><td>1200원</td><td>0%</td><td>1200원</td><td>100개</td></tr>
                  </tbody>
                </table>

                <!-- GS 테이블 (초기 숨김) -->
                <table class="table table-striped table-bordered table-hover" id="gsTable" style="display:none;">
                  <thead>
                    <tr>
                      <th>상품번호</th><th>상품명</th><th>가격</th><th>할인율</th><th>할인가격</th><th>재고</th>
                    </tr>
                  </thead>
                  <tbody>
                    <tr><td>2001</td><td>GS 도시락</td><td>5000원</td><td>5%</td><td>4750원</td><td>50개</td></tr>
                    <tr><td>2002</td><td>GS 핫바</td><td>1500원</td><td>0%</td><td>1500원</td><td>80개</td></tr>
                  </tbody>
                </table>

                <!-- 콤보 테이블 (초기 숨김) -->
                <table class="table table-striped table-bordered table-hover" id="comboTable" style="display:none;">
                  <thead>
                    <tr>
                      <th>상품번호</th><th>상품명</th><th>가격</th><th>할인율</th><th>할인가격</th><th>재고</th>
                    </tr>
                  </thead>
                  <tbody>
                    <tr><td>3001</td><td>콤보세트1</td><td>10000원</td><td>20%</td><td>8000원</td><td>20개</td></tr>
                    <tr><td>3002</td><td>콤보세트2</td><td>15000원</td><td>25%</td><td>11250원</td><td>15개</td></tr>
                  </tbody>
                </table>

              </div> <!-- table-responsive -->
            </div> <!-- card-content -->
          </div> <!-- card -->
        </div> <!-- col-md-12 -->
      </div> <!-- row -->

    </div> <!-- page-inner -->
  </div> <!-- page-wrapper -->

</div> <!-- wrapper -->

<!-- JS 절대경로 -->
<script src="${pageContext.request.contextPath}/admin/assets/js/jquery-1.10.2.js"></script>
<script src="${pageContext.request.contextPath}/admin/assets/js/bootstrap.min.js"></script>
<script src="${pageContext.request.contextPath}/admin/assets/js/jquery.metisMenu.js"></script>
<script src="${pageContext.request.contextPath}/admin/assets/js/custom-scripts.js"></script>

<!-- 관리용 스크립트 -->
<script src="${pageContext.request.contextPath}/admin/assets/js/adminProduct.js"></script>

</body>
</html>