var row = document.createElement('tr');
for (var i = 0; i < columns.length; i ++) {
var th = document.createElement(columnType);
var text = document.createTextNode(columns[i]);
th.appendChild(text);
row.appendChild(th);
var row = document.createElement('tr');
for (var i = 0; i < columns.length; i ++) {
var th = document.createElement(columnType);
var text = document.createTextNode(columns[i]);
th.appendChild(text);
row.appendChild(th);