// 根据类名获取元素

function getElementsByClass(oParent,sClass){

    var aResult = [];

    var aNode = oParent.getElementsByTagName("*");

    for(var i=0; i<aNode.length; i++){

        if(aNode[i].className == sClass){

            aResult.push(aNode[i]);

        }

    }

    return aResult;

}