JavaScript校验邮箱

      const emailReg = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/g
      if (!emailReg.test(this.user.email) || !this.user.email) {
        this.$showMessage('danger', '请输入正确的邮箱格式')
        return
      }