兼容低版本ie的getByClass方法

function getByClass(oParent,sClass){
    
    if(oParent.getElementsByClassName){
                //本除返回的是dom集合，类数组而非数组
        return oParent.getElementsByClassName(sClass);
    }
    
    var result = [];
    var re = new RegExp("\\b"+sClass+"\\b");
    
    var aEle = oParent.getElementsByTagName("*");
    
    for(var i = 0; i < aEle.length; i++){
        if( re.test(aEle[i].className) ){
            result.push(aEle[i]);
        }
    }
        //本除返回数组
    return result;
}