easyui 改变单元格背景颜色

<table id="roleList">
        <thead>
          <tr>
              <th data-options="field:‘ck‘,checkbox:true"></th>  
              <th data-options="field:‘monitor_item_code‘,width:70,align:‘center‘">XXX</th>
              <th data-options="field:‘gap_value‘,width:70,align:‘center‘">XXX</th>
              <th data-options="field:‘remark‘,width:70,align:‘center‘">XXX</th>
              <th data-options="field:‘alarm_role‘,width:70,align:‘center‘,formatter:alarmRole">XXX</th>
              <th data-options="field:‘flag‘,width:70,align:‘center‘,formatter:flag,styler:flagColor">状态</th>
              <th data-options="field:‘operate‘,width:80,align:‘center‘,formatter:formatOper">操作</th>
          </tr>
         </thead>
    </table>

function flagColor(val, row, index) {
    if (val == ‘1‘) {
        return ‘background:#B9F3B9‘;
    } else if (val == 0) {
        return ‘background:#FFCCCC‘;
    }
}
function flag(val, row, index) {
    return ‘<a href="javascript:void(0)" class="start"  onclick="changeFlag(‘ + index + ‘,1)"></a><a href="javascript:void(0)" class="stop" onclick="changeFlag(‘ + index + ‘,0)"></a>‘;
}