Vue

HTML

<div id="app">
  <input id="testinput1" v-model="testval1" v-test />
  <input id="testinput2" v-model="testval2" v-test />
</div>

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

del {
  color: rgba(0, 0, 0, 0.3);
}

Vue

Vue.directive('test', {
  bind: (el) => {
  	console.log(el.id + " bound")
  },
  update: (el) => {
  	console.log(el.id + " updated")
  }
})

new Vue({
  el: "#app",
  data: {
  	testval1: null,
  	testval2: null,
  },
  methods: {
  }
})