通过ClassName获取元素的函数 getElementsByClassName

function getElementsByClassName(n) {
    var el = [],
        _el = document.getElementsByTagName('*');
    for (var i=0; i<_el.length; i++ ) {
        if (_el[i].className == n ) {
            el[el.length] = _el[i];
        }
    }
    return el;
}

应用

var subMenus = getElementsByClassName('subMenu');
    for (var i=0; i<dropMenus.length; i++) {
   if (subMenus[i]!=OBJ_VIEW)
   {
    subMenus[i].style.display = 'none';
   }
}

<div className="subMenu">1</div>

<div className="subMenu">2</div>

<div className="subMenu">3</div>