Not every bit of info you add to a component is state. Sometimes you need to add some metadata that gives other components more information.

For example, if you're building a bunch of different widgets for an analytics dashboard like Google Analytics:

If you want the layout to know how many columns each widget should take up, you can add that directly on the component as metadata:

export default {
  name: 'LiveUsersWidget',
  // 👇 Just add it as an extra property
  columns: 3,
  props: {
    // ...
  },
  data() {
    return {
      //...
    };
  },
};

You'll find this metadata as a property on the component:

import LiveUsersWidget from './LiveUsersWidget.vue';
const { columns } = LiveUsersWidget;

You can also access the metadata from within the component through the special $options property:

export default {
  name: 'LiveUsersWidget',
  columns: 3,
  created() {
    // 👇 `$options` contains all the metadata for a component
    console.log(`Using ${this.$options.metadata} columns`);
  },
};

Just keep in mind that this metadata is the same for each instance of the component, and is not reactive.

Other uses for this include (but are not limited to):

• Keeping version numbers for individual components
• Custom flags for build tools to treat components differently
• Adding custom features to components beyond computed props, data, watchers, etc.
• and many more I can't think of!

See a live example here: https://codesandbox.io/s/vue-metadata-bew9j?file=/src/App.vue