title: Is it possible to use the computed properties to compute another properties in Vue?
body: <p>If I have a two computed properties like this,</p>
  
  <pre><code>computed: {
    id: function(){ return this.$route.query.id; },
    hasId: function(){ return this.$route.query.id !== undefined; }
  }
  </code></pre>
  
  <p>how can I use <code>id</code> to compute <code>hasId</code> like this pseudo-code?</p>
  
  <pre><code>computed: {
    id: function(){ return this.$route.query.id; },
    hasId: function(){ return id !== undefined; }
  }
  </code></pre>