To access this inside a nested function create a local variable and store this in this valiable, like the example above

component.vue

methods: {
    save (evt) {
      let self = this
      evt.preventDefault()
      this.$validator.validateAll().then((result) => {
        if (result) {
          EventBus.$emit('startLoading')
          dbUser.save(this.user)
            .then((resp) => {
              EventBus.$emit('stoptLoading')

              if (!resp.erro) {
                swal({
                  title: i18n.tc('general.successsave'),
                  type: 'success'
                })
              } else {

              }
            })
            .catch((e) => {
              EventBus.$emit('stoptLoading')
              if (e.data.error.code === 11000) {
                swal({
                  title: i18n.tc('user.duplicatedEmail'),
                  type: 'error'
                }).then(() => {
                  self.$refs.email.focus()
                })
              } else {
                swal({
                  title: e.data.message,
                  type: 'error'
                })
              }
            })
        }
      })
    },