<script>

function createTHead(){

    var x=document.getElementById("myTable");

    if (!x.tHead){

    var header=x.createTHead();

    var row=header.insertRow(0);

    var cell=row.insertCell(0);

    cell.innerHTML="<b>这是个表头</b>";

    }

}

function deleteTHead(){

    document.getElementById("myTable").deleteTHead();

}

</script>

<table id="myTable" border="1">

    <tr>

        <td>cell 1</td>

        <td>cell 2</td>