<div id="app">

  <div>
    <p>Counter: {{ counter }}</p>
  </div>
  
  <button @click="addCounterFunction">Add Counter (Function)</button>
 
  <button @click="addCounterArrowFunction">Add Counter (Arrow Function)</button>
</div>

 <script src="https://cdn.jsdelivr.net/npm/vue@2.5.13/dist/vue.js"></script>
var app = new Vue({
  el: '#app',
  data: {
    counter: 0
  },
  methods: {
    addCounterFunction: function() {
      this.counter++
    },
     addCounterArrowFunction: () => {
      this.counter++
    },
  }
})

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External JavaScript

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