var table = document.getElementsByTagName("table")[0];
rows = table.rows;
var rownum = table.rows.length;
var i = 0;
for(;idocument.body.appendChild("第"+i+"行有"+rows[i].cells.length+"个单元格");
}
var tdnode=document.getElementById("szctr").childNodes;
alert("szctr下面有"+tdnode.length+“个td”);