Edit in JSFiddle

new Vue({
  el: "#app",
  data: {
    mac: "AA:BB:8c:DD:12:FF",
  },
  computed: {
    output() {
      return /^([0-9a-fA-F]{2}[:.-]?){5}[0-9a-fA-F]{2}$/g.test(this.mac);
    }
  },
  methods: {},
  mounted() {}
})