code: function query(selector) {
    var container = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : document;
    var toArray = arguments[2];
  
    var retNodeList = container.querySelectorAll(selector);
    return toArray ? _Array$from(retNodeList) : retNodeList;
  }
docs: 根据选择器查询目标元素
  @param {String} selector 选择器,用于 querySelectorAll
  @param {HTMLElement} container 父容器
  @param {Boolean} toArray 强制输出为数组
  @return {NodeList|Array}