JS判断是否有滚动条

function hasScrolled(el, direction = "vertical") {
    if(direction === "vertical") {
        return el.scrollHeight > el.clientHeight;
    } else if(direction === "horizontal") {
        return el.scrollWidth > el.clientWidth;
    }
}

在线Demo：http://codepen.io/willshawzq/pen/PPVdNX