App.js

<script>
export default {
  data() {
    return {
      counter: 0,
    };
  },
  methods: {
    clicked() {
       this.counter ++;
    },
  },
  directives: {
    myOn: {
      bind(el, binding) {
        const event = binding.arg;
        const fn = binding.value;

        el.addEventListener(event, fn);
      }
    }
  }
};
</script>