var varTr = event.srcElement.parentElement.parentElement;
var tbl = varTr.parentElement;
var index=event.srcElement.parentElement.parentElement.rowIndex;
var nextrow = tbl.rows[index + 1] //下一行
var tbl = varTr.parentElement;
var index=event.srcElement.parentElement.parentElement.rowIndex;
var nextrow = tbl.rows[index + 1] //下一行
继续parentElement向上层得到table对象 然后[table].rows[index+1]