text: /* @flow */
  
  import { warn } from 'core/util/index'
  
  export * from './attrs'
  export * from './class'
  export * from './element'
  
  /**
   * Query an element selector if it's not an element already.
   */
  export function query (el: string | Element): Element {
    if (typeof el === 'string') {
      const selected = document.querySelector(el)
      if (!selected) { // TODO 这有什么意义吗？
        process.env.NODE_ENV !== 'production' && warn(
          'Cannot find element: ' + el
        )
        return document.createElement('div')
      }
      return selected
    } else {
      return el
    }
  }
  