<script src="https://unpkg.com/vue/dist/vue.js"></script>

<div id="no-mode-demo" class="demo">

  <transition name="no-mode-fade">

    <button v-if="on" key="on" @click="on = false">

      on

    </button>

    <button v-else="" key="off" @click="on = true">

      off

    </button>

  </transition>

</div>

<script>

new Vue({

  el: '#no-mode-demo',

  data: {

    on: false

  }

})

</script>

<style>

.no-mode-fade-enter-active, .no-mode-fade-leave-active {

  transition: opacity .5s

}

.no-mode-fade-enter, .no-mode-fade-leave-active {

  opacity: 0

}

</style>