title: Vuex - transform store object without altering original
body: <p>I'm trying to copy a store object for local transformation but my alteration function is changing the original store object also. I'm using <code>...mapState[&quot;storeObject&quot;]</code></p>
  <p>This is basically what's happening:</p>
  <pre><code>state.storeOjb = &quot;original value&quot; 
  this.local = storeOjb ;
  this.local = &quot;altered version of storeOjb&quot;
  
  storeOjb === &quot;original value&quot; // false -- why?
  </code></pre>