title: Vue.js modify computed property?
body: <p>I am trying to modify a <code>moment.js</code> instance that resides in <code>vue.js</code> computed property like so.</p>
  
  <pre><code>computed: {
      currentDate() {
          return moment();
      }
  }
  </code></pre>
  
  <p>Whenever I try to call it with a method like this one, nothing happens:</p>
  
  <pre><code>methods: {
      prevMonth() {
          this.currentDate = moment(this.currentDate).subtract(1, 'months');
      }
  }
  </code></pre>
  
  <p>I am guessing this is because computed properties only allow to act as getters(and optionally setters). How can I change this behavior though?</p>
  
  <p>I oversimplified the example since I am using the cmoputed property to fetch data from my <code>vuex</code> store. I am no longer able to manipulate it though.</p>
  
  <p>Is there some way I can populate a local <code>currentDate</code> property with the <code>vuex</code> store's value so I can still manipulate it and add months, etc?</p>
  
  <p>I have though about using the <code>mounted</code> property for this but I only mount my component once. Any help is welcome.</p>