js 获取子节点函数 (兼容FF与IE)

function getfirstchild(obj) {
var result = obj.firstchild;
while (!result.tagname) {
result = result.nextsibling;
}
return result;
}

function getnextchild(obj) {
var result = obj.nextsibling;
while (!result.tagname) {
result = result.nextsibling;
}
return result;
}