vite.config.ts, svelte sample

.env

VITE_API_URL="http://localhost:4000"
VITE_API_KEY=""

package.json

{
  "name": "svelte_sample1",
  "private": true,
  "version": "0.0.0",
  "type": "module",
  "scripts": {
    "dev": "vite",
    "build": "vite build",
    "preview": "vite preview",
    "check": "svelte-check --tsconfig ./tsconfig.json"
  },
  "devDependencies": {
    "@sveltejs/vite-plugin-svelte": "^3.0.1",
    "@tsconfig/svelte": "^5.0.2",
    "svelte": "^4.2.8",
    "svelte-check": "^3.6.2",
    "svelte-spa-router": "^4.0.1",
    "tslib": "^2.6.2",
    "typescript": "^5.2.2",
    "vite": "^5.0.8"
  }
}

vite.config.ts

import { defineConfig } from 'vite'
import { svelte } from '@sveltejs/vite-plugin-svelte'

// https://vitejs.dev/config/
export default defineConfig(({ mode }) => {
  if (mode === 'production') {
    return {
      plugins: [svelte()], 
      define: {
        "process.env.NODE_ENV": '"production"',
      },  
      build: {
        lib: {
          entry: [
            './src/main.ts',
          ],
          formats: ['es'],
          fileName: '[name]',
        },
        rollupOptions: {
          output: {
            dir: './dist/static'
          }
        },
        emptyOutDir: false,
        copyPublicDir: false
      }   
    }
  }else{
    return {
      plugins: [svelte()], 
    }
  }
})

/*

*/