js operation class

//判断有无
function hasClass(ele, cls) {
    return ele.className.match(new RegExp("(\\s|^)" + cls + "(\\s|$)"));
}

//添加
function addClass(ele, cls) {
    if (!this.hasClass(ele, cls)) ele.className += " " + cls;
}

//删除
function removeClass(ele, cls) {
    if (hasClass(ele, cls)) {
        let reg = new RegExp("(\\s|^)" + cls + "(\\s|$)");
        ele.className = ele.className.replace(reg, " ");
    }
}