isServer

const isServer: boolean

This indicates that the code is being run as the server or browser bundle. As the underlying runtimes export this as a constant boolean it allows bundlers to eliminate the code and their used imports from the respective bundles.

import { isServer } from "solid-js/web";

if (isServer) {
  // I will never make it to the browser bundle
} else {
  // won't be run on the server;
}