动态添加类名

    <ul ref="ulRef">
      <li class="test1 test2">项目一</li>
      <li class="test1 test2">项目二</li>
      <li class="test1 test2">项目三</li>
    </ul>

export const addClass = (el, className) => {
  if (_hasClass(el, className)) return
  let newClass = el.className.split(‘ ‘)
  newClass.push(className)
  el.className = newClass.join(‘ ‘)
}

// 判断当前元素中是否有该类名
const _hasClass = (el, className) => {
  const reg = new RegExp(‘(^|\\s)‘ + className + ‘(\\s|$)‘)
  return reg.test(el.className)
}

import { addClass } from ‘@utils/utils‘

  mounted() {
    this._addClass()
  },
  methods: {
    _addClass() {
      let list = this.$refs.ulRef.children
      list.forEach((item) => {
        addClass(item, ‘test3‘)
      })
    }
  }