Building Your App

Building a SvelteKit consists of two stages. First the production build is run. This will create a client and a server build which are later consumed by the corresponding environments. Prerendering is executed at this stage, if enabled. The second step is to adapt the output to your deployment target using adapters (more on that in the later sections).

During the buildpermalink

SvelteKit will load your +page/layout(.server).js files (and all files they import) for analysis during the build. This could lead to code eagerly running which you want to avoid at that stage. Wrap the code in question with building from $app/environment:

ts
import { building } from '$app/environment';
import { setupMyDatabase } from '$lib/server/database';
 
if (!building) {
  setupMyDatabase();
}
 
export function load() {
  // ...
}

Preview your apppermalink

Run the preview script to look at your app locally after the production build is done. Note that this does not yet include adapter-specific adjustments like the platform object.