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; 
}