在使用＜%=request.getContextPath()%＞时遇到的错误

正确代码：
window.location.href = “<%=request.getContextPath()%>/dept/delete?deptno=”+dno;
或
window.location.href = “<%=request.getContextPath()%>”+“/dept/delete?deptno=”+dno;

错误代码：
window.location.href = <%=request.getContextPath()%>+“/dept/delete?deptno=”+dno;