js给html下拉框Select赋值

<select id="department" onchange="" style="width:150px;">
</select>

departmentList = oBook.departmentList;
var departmentSelect = document.getElementById("department");
departmentSelect.options.length=0;/**清空下拉框的值*/
if((departmentList!=null)&&(departmentList.length!=0)) {
      for(var i=0; i<=departmentList.length; i++){
      　　var op = new Option();
     　　 op.text=departmentList[i].name;
     　　 op.value=departmentList[i].id;
      　　departmentSelect.options.add(op);
      }
}