Using vue-screen in SSR causes hydration errors about vue-screen

[reegodev]

TL:DR Use v-show instead of v-if to show/hide components based on resolution when server rendering.

Full explanation
When server rendering a Vue application and you conditionally display a node in the DOM and tie that condition to the screen dimensions, you have to remember that the server must "choose" arbitrarily a default window resolution, because there is no such thing as window on the server.

This library uses a resolution of 410x730 when server rendering, which is the default resolution of GoogleBot. I decided to go with these dimensions to force the mobile-first approach that also most CSS frameworks adopted and is considered good practice.
I've also considered exposing a config to allow users to alter the server resolution, but as mentioned above i'd like to force a mobile-first approach, and did not find any compelling use cases where you'd like to render for desktop rather than for mobile.

That being said, if you really need custom server resolution i'm open for discussion

[reegodev]

You are right about loading unneeded components, with v-show you get to load everything even if you don't really need it, and that is indeed a waste of resources for the end user.

If you really wanna avoid loading unneeded components in Nuxt, you can try this:

// Index.vue
<template>
  <div>
    <client-only>
      <MyComponent v-if="$screen.lg" />
    </client-only>
  </div>
</template>
<script>
export default {
  components: {
    MyComponent: () => import(/* webpackChunkName: "my-component" */ '~/components/MyComponent.vue'),
  }
}
</script>

Pros:

• The <client-only> component won't render it on the server, avoiding hydration issues
• The condition on a lazy loaded component will make the browser download the component only when the condition is true

Cons:

• MyComponent contents will never be indexed by crawlers

I'm afraid the point really lies on SEO concerns: If you want your component contents to be indexed, then your users must be penalised by downloading potentially unneeded scripts. If you don't care about indexing, then your component can just be rendered on demand on the client.

[nathanchase]

@reegodev Thanks very much for the explanation!

That does make sense to err on the side of a mobile viewport width for a potential Googlebot (Smartphone) crawl. I think ultimately perhaps it makes the use of this type of library unhelpful to achieve the goal of only lazily loading components for a specific user depending on their viewport (For example: a TabBar component that only loads and shows for a mobile user, but it's unneeded and never loaded for a desktop user).

Using a v-show is not much different than just using CSS classes to show/hide elements, if all the components load in the background anyways.

It's a struggle, in the sense that there are definitely different amounts of content that needs to be loaded and displayed for a mobile user (for UX and bandwidth reasons). If only we had something that was native within the browser like srcset that could dynamically load Vue components (instead of images) according to device resolution - and that it would work when using a SSR framework (in my case, Nuxt).

[nathanchase]

Thanks for the discussion and insight! Will close the issue.