Vue.js Array Values Change

HTML

<div id="app">
  <button @click="changeValueOnArray()">
    Change Value on Array
  </button>
  {{ array }}
  <button @click="changeArray()">
    Change Array
  </button>
</div>

JavaScript

var app = new Vue({
  el: '#app',
  data: {
    array: [1]
  },
  methods: {
    changeArray: function() {
      this.array = [false,false,false];
    },
    changeValueOnArray: function() {
      this.array[0] = false;
    }
  }
})