Vue

HTML

<div id="app">
  <pre>cat2.reference = {{ cat2.reference }}</pre>
</div>

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

del {
  color: rgba(0, 0, 0, 0.3);
}

Vue

new Vue({
  el: "#app",
  data: () => {
    const data = {
      cat1 : {name: "Category 1", reference : false},
      cat2 : {name: "Subcategory 2", get reference() { return data.cat1 }}
    }
    console.log(data.cat2.reference)
    return data
  },
  mounted () {
  	setTimeout(() => this.cat1.name = 'Foo', 2000)
  }
})