How to import Firebase only on client in Sapper?

Question

I\'m importing Firebase into my Sapper application, I do not want the imports to be evaluated on the server. How do I make sure imports are only on the client-side?

I

Answer 1

I was able to import firebase using ES6. If you are using rollup you need to consfigure namedExports in commonjs plugin:

//--- rollup.config.js ---
...
commonjs({
        namedExports: {
          // left-hand side can be an absolute path, a path
          // relative to the current directory, or the name
          // of a module in node_modules
          'node_modules/idb/build/idb.js': ['openDb'],
          'node_modules/firebase/dist/index.cjs.js': ['initializeApp', 'firestore'],
        },
      }),

The you can use it like this:

//--- db.js ---
import * as firebase from 'firebase';
import 'firebase/database';
import { firebaseConfig } from '../config'; //<-- Firebase initialization config json

// Initialize Firebase
firebase.initializeApp(firebaseConfig);
export { firebase };
// Initialize db
export const db = firebase.firestore();

and maybe use it in a service like such:

// --- userService.js ----
import { db } from './common';

const usersCol = db.collection('users');
export default {
  async login(username, password) {
    const userDoc = await usersCol.doc(username).get();
    const user = userDoc.data();
    if (user && user.password === password) {
      return user;
    }
    return null;
  },
};

EDITED Full rollup config

/* eslint-disable global-require */
import resolve from 'rollup-plugin-node-resolve';
import replace from 'rollup-plugin-replace';
import commonjs from 'rollup-plugin-commonjs';
import svelte from 'rollup-plugin-svelte';
import babel from 'rollup-plugin-babel';
import { terser } from 'rollup-plugin-terser';
import config from 'sapper/config/rollup';
import { sass } from 'svelte-preprocess-sass';
import pkg from './package.json';

const mode = process.env.NODE_ENV;
const dev = mode === 'development';
const legacy = !!process.env.SAPPER_LEGACY_BUILD;

// eslint-disable-next-line no-shadow
const onwarn = (warning, onwarn) =>
  (warning.code === 'CIRCULAR_DEPENDENCY' && warning.message.includes('/@sapper/')) || onwarn(warning);

export default {
  client: {
    input: config.client.input(),
    output: config.client.output(),
    plugins: [
      replace({
        'process.browser': true,
        'process.env.NODE_ENV': JSON.stringify(mode),
      }),
      svelte({
        dev,
        hydratable: true,
        emitCss: true,
        preprocess: {
          style: sass(),
        },
      }),
      resolve({
        browser: true,
      }),
      commonjs({
        namedExports: {
          // left-hand side can be an absolute path, a path
          // relative to the current directory, or the name
          // of a module in node_modules
          'node_modules/idb/build/idb.js': ['openDb'],
          'node_modules/firebase/dist/index.cjs.js': ['initializeApp', 'firestore'],
        },
      }),

      legacy &&
        babel({
          extensions: ['.js', '.mjs', '.html', '.svelte'],
          runtimeHelpers: true,
          exclude: ['node_modules/@babel/**'],
          presets: [
            [
              '@babel/preset-env',
              {
                targets: '> 0.25%, not dead',
              },
            ],
          ],
          plugins: [
            '@babel/plugin-syntax-dynamic-import',
            [
              '@babel/plugin-transform-runtime',
              {
                useESModules: true,
              },
            ],
          ],
        }),

      !dev &&
        terser({
          module: true,
        }),
    ],

    onwarn,
  },

  server: {
    input: config.server.input(),
    output: config.server.output(),
    plugins: [
      replace({
        'process.browser': false,
        'process.env.NODE_ENV': JSON.stringify(mode),
      }),
      svelte({
        generate: 'ssr',
        dev,
      }),
      resolve(),
      commonjs(),
    ],
    external: Object.keys(pkg.dependencies).concat(require('module').builtinModules || Object.keys(process.binding('natives'))),

    onwarn,
  },

  serviceworker: {
    input: config.serviceworker.input(),
    output: config.serviceworker.output(),
    plugins: [
      resolve(),
      replace({
        'process.browser': true,
        'process.env.NODE_ENV': JSON.stringify(mode),
      }),
      commonjs(),
      !dev && terser(),
    ],

    onwarn,
  },
};