：js在table插入一条空白行tr

function insertlasttr(myTable){

var table = document.getElementById(myTable);

var existingRow = table.rows[0];

var newRow = table.insertRow(-1); 

for (var k = 0; k < table.rows[0].cells.length; k++) {

var newCell = newRow.insertCell(k);

newCell.rowSpan = existingRow.cells[k].rowSpan;

newCell.colSpan = existingRow.cells[k].colSpan;

newCell.style.cssText = existingRow.cells[k].style.cssText;

}

}