用原生JS实现getElementsByClass

function getByClass(oParent,sClass){
    var aEle = oParent.getElementsByTagName(‘*‘);
    var result = [];
    var re = new RegExp(‘\\b‘ + sClass + ‘\\b‘,‘i‘);
    
    for(var i=0;i<aEle.length;i++){
        if(re.test(aEle[i].className)){
            result.push(aEle[i]);
        }
    }
    
    return result;
}