根据TD得到TR

var tdObj=document.getElementById(“tdObject”);
var trObj=null;

trObj=tdObj;
do{
	trObj=trObject.parentElement;
}while(trObj.tagName="TR");
//得到前面一个TD
var rowIndex;
var cellIndex;
rowIndex=trObj.rowIndex;
celIndex=tdObj.cellIndex;

trObj.cells[cellIndex-1]