mixins.vue

<script>
// mixins.js

export default {
  props: {
    isOpen: {
      default: true
    }
  },
  data() {
    return {
      shown: this.isOpen
    }
  },
  methods: {
    hide() {
      this.shown = false
    },
    show() {
      this.shown = true
    },
    toggle() {
      this.shown =! this.shown
    }
  }
}
</script>