storybook/code/lib/builder-vite/src/build.ts

import { build as viteBuild } from 'vite';
import { commonConfig } from './vite-config';

import type { ExtendedOptions } from './types';

export async function build(options: ExtendedOptions) {
  const { presets } = options;

  const config = await commonConfig(options, 'build');
  config.build = {
    outDir: options.outputDir,
    emptyOutDir: false, // do not clean before running Vite build - Storybook has already added assets in there!
    sourcemap: true,
  };

  const finalConfig = await presets.apply('viteFinal', config, options);

  await viteBuild(finalConfig);
}