gatsby-node.ts

import { GatsbyNode } from 'gatsby'
/* eslint-disable func-names */
export { createPages } from './src/gatsby/createPages'
export { onCreatePage } from './src/gatsby/onCreatePage'

export const onCreateWebpackConfig: GatsbyNode['onCreateWebpackConfig'] = ({
  stage,
  actions,
  getConfig,
}) => {
  if (stage === 'build-html') {
    actions.setWebpackConfig({
      // Don't bundle modules that reference browser globals such as `window` and `IDBIndex` during SSR.
      // See: https://github.com/gatsbyjs/gatsby/issues/17725
      externals: getConfig().externals.concat(function (
        _context: any,
        request: string,
        callback: (arg0: null | undefined, arg1: string | undefined) => void
      ) {
        // Exclude bundling firebase* and react-firebase*
        // These are instead required at runtime.
        if (/^@?(react-)?firebase(.*)/.test(request)) {
          console.log(`Excluding bundling of: ${request}`)

          return callback(null, `umd ${request}`)
        }

        callback(undefined, undefined)
      }),
    })
  }
}