JavaScript - funcion dibuja campos

function myCreateFunction() {

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

    var row = table.insertRow(0);

    var cell1 = row.insertCell(0);

    var cell2 = row.insertCell(1);

    cell1.innerHTML = "<textarea  rows='1'   cols='35'      name='plan[]'></textarea>";

    cell2.innerHTML = "<textarea  rows='1'   cols='35'      name='plan[]'></textarea>";

}

function myDeleteFunction() {

    document.getElementById("myTable").deleteRow(0);

}

</script>

function addRow(tableID) {

            var table = document.getElementById('myTable');

            var rowCount = table.rows.length;

            var row = table.insertRow(rowCount);

            var cell1 = row.insertCell(0);

            var element1 = document.createElement("input");

            element1.type = "text";

            element1.name = "plan[]";

            cell1.appendChild(element1);

            var cell2 = row.insertCell(1);

            var element2 = document.createElement("input");

            element2.type = "text";

            element2.name = "plan[]";

            cell2.appendChild(element2);

        }

        function deleteRow(tableID) {

                var table = document.getElementById('myTable');

                var rowCount = table.rows.length;

            if (rowCount > 1){

                var del = rowCount -1 ;

                table.deleteRow(del);

            } else {

                alert ('No puedes borrar todos los elementos!');

            }

        }