<table>
    <thead>
        <tr>
            <g:sortableColumn property="dname" title="${message(code: 'devices.dname.label', default: 'Dname')}" />

            <g:sortableColumn property="owner" title="${message(code: 'devices.owner.label', default: 'Owner')}" />

            <g:sortableColumn property="serailNumber" title="${message(code: 'devices.serailNumber.label', default: 'Serail Number')}" />

            <g:sortableColumn property="supportingAndroidVersion" title="${message(code: 'devices.supportingAndroidVersion.label', default: 'Supporting Android Version')}" />

        </tr>
    </thead>
    <tbody>
        <g:each in="${Devices.list()}" status="i" var="devicesInstance">
            <tr class="${(i % 2) == 0 ? 'even' : 'odd'}">

                <td>${fieldValue(bean: devicesInstance, field: "dname")}</td>

                <td>${fieldValue(bean: devicesInstance, field: "owner")}</td>

                <td>${fieldValue(bean: devicesInstance, field: "serailNumber")}</td>

                <td>${fieldValue(bean: devicesInstance, field: "supportingAndroidVersion")}</td>
                <td>
                    <g:checkBox name="myCheckbox${i}" value="${false}" />
                </td>
            </tr>
        </g:each>
    </tbody>
</table>
<button class="btn btn-xs btn-info pull-right" type="button" onclick=getvalue()>Save Device</button>

function getvalue(){
                   var p = document.getElementById('mytable').rows.length;
                  alert(p)//I am getting the row count
                   var checkboxes = document.getElementsByName('myCheckbox[]');
                                   var vals = "";
                   for (var i=0, n=p-1;i<n;i++) {

                     if (checkboxes[i].checked)
                     {
                     vals += ","+checkboxes[i].value;
                    alert(val)
                     }
                   }

                 if (vals) vals = vals.substring(1);

                   }