How to change cell value?

How to change cell value?

I have a table as below, I hope the "ecCurrent" will be changed to "no rank" when I unchecked dat.ECRank, what can I do?
  1. <table cellspacing="0" class="caption" cellpadding="1">
        <tr>
            <td class="pad" rowspan=3 style="text-align:right;width:100px">ＣＯＭ</td>
            <td class="item_h">Rank</td>
            <td class="item_h">ecCurrent</td>
            <td class="item_h">eBest</td>
            <td class="item_h">Tokka</td>
            <td class="item_h">Pop</td>
        </tr>
        <tr>
            <td class="item_kakaku"><%=dat.Rank1%></td>
            <td class="item_kakaku"><%=dat.ECRank%></td>
            <td class="item_kakaku"><%=dat.EBRank%></td>
            <td class="item_kakaku"><%=dat.TKRank%></td>
            <td class="item_kakaku" rowspan=2><%=dat.KakakuRanking%></td>
        </tr>
        <tr>
            <td class="item_kakaku">Target</td>
            <td class="item_kakaku"><%=TAG_InputCheckBox("ec_target", "1", dat.ECTarget)%></td>
            <td class="item_kakaku"><%=TAG_InputCheckBox("eb_target", "1", dat.EBTarget)%></td>
            <td class="item_kakaku"><%=TAG_InputCheckBox("tk_target", "1", dat.TKTarget)%></td>
        </tr>
    </table>