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How to Bundle Your JavaScript Projects Using webpack

· 7 min read


I use webpack to bundle some JS scripts today, see openapi-scripts/pull/16. The following lists details of the project and reasons for bundling:

Step 1. Install webpack-cli

To install webpack-cli, run the following command. For more information about the directory structure, refer to Basic setup.

yarn add webpack webpack-cli --dev

Step 2. Configure a webpack.config.js

For more details about configuration in webpack, see Configuration.

  • Create a webpack.config.js file in the root directory of the repository.

  • Then, configure the webpack.config.js file.


    The entry is ./src/main.js in the repository.

    const path = require('path');

    module.exports = {
    entry: './src/main.js',
    output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'dist'),
  • Use the preceding configuration file to generate a dist/main.js file.

    npx webpack --config webpack.config.js
  • Oops! An error occurs after executing the preceding command.

    BREAKING CHANGE: webpack < 5 used to include polyfills for node.js core modules by default.
    This is no longer the case. Verify if you need this module and configure a polyfill for it.

    If you want to include a polyfill, you need to:
    - add a fallback 'resolve.fallback: { "http": require.resolve("stream-http") }'
    - install 'stream-http'
    If you don't want to include a polyfill, you can use an empty module like this:
    resolve.fallback: { "http": false }
    @ ./node_modules/@apidevtools/json-schema-ref-parser/lib/options.js 9:21-48
    @ ./node_modules/@apidevtools/json-schema-ref-parser/lib/normalize-args.js 3:16-36
    @ ./node_modules/@apidevtools/json-schema-ref-parser/lib/index.js 6:22-49
    @ ./src/deref.js 2:19-65
    @ ./src/main.js 3:14-35
  • Then, I Google the error message and find the answer in Stack Overflow and Targets in webpack. To use node webpack to compile for usage, add the target: 'node' into the webpack.config.js file.

    const path = require('path');

    module.exports = {
    target: 'node',
    entry: './src/main.js',
    output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'dist'),
  • Try to execute npx webpack --config webpack.config.js again and a warning message shows:

    $ npx webpack --config webpack.config.js
    asset main.js 484 KiB [emitted] [minimized] (name: main) 1 related asset
    WARNING in configuration
    The 'mode' option has not been set, webpack will fallback to 'production' for this value.
    Set 'mode' option to 'development' or 'production' to enable defaults for each environment.
    You can also set it to 'none' to disable any default behavior. Learn more:

    webpack 5.74.0 compiled with 1 warning in 1990 ms
  • To enables deterministic mangled names for modules and chunks, add mode: 'production' into the webpack.config.js file.

    const path = require('path');

    module.exports = {
    target: 'node',
    entry: './src/main.js',
    output: {
    filename: 'main.js',
    path: path.resolve(__dirname, 'dist'),
    mode: 'production',
  • Try to execute npx webpack --config webpack.config.js again and it works to generate a dist/main.js and dist/main.js.LICENSE.txt.

    $ npx webpack --config webpack.config.js
    json modules 155 KiB
    modules by path ./node_modules/har-schema/lib/ 6.93 KiB 18 modules
    modules by path ./node_modules/ajv/lib/ 5.58 KiB
    ./node_modules/ajv/lib/refs/json-schema-draft-06.json 2.46 KiB
    + 2 modules
    ./node_modules/mime-db/db.json 143 KiB
    webpack 5.74.0 compiled successfully in 2524 ms
  • To test the generated dist/main.js file, run the following command.

    $ node dist/main.js --help
    Usage: postprocess [options] [command]

    Postprocess an OpenAPI document for ReDoc

    -V, --version output the version number
    -h, --help display help for command

    deref <in-filename> [out-filename] Use $RefParser to dereference a JSON schema
    importmd <in-filename> <md-folder> <gen-md> Merge markdown files in <md-folder> to a markdown <gen-file>, and import
    it as $ref to JSON info.description.
    addlogo <in-filename> <url> <alt> <href> Add a logo to JSON info.x-logo
    gencode <in-filename> Generate sample code to JSON as x-code-samples
    devtier <in-filenam> Add sample for creating a dev tier cluster
    help [command] display help for command

Step 3. Modify the Dockerfile

Modify the Dockerfile as follows:

FROM node:16
COPY package.json yarn.lock ./src/ .
RUN yarn install
ENTRYPOINT ["node", "/app/main.js"]
  • The new Dockerfile contains two stages. For more information about multi-stage builds, refer to Use multi-stage builds.

  • The first stage is a build stage, which tells Docker to:

    • build an image starting with the node:16 image and name it build

    • copy all files in the repository to the /build folder


      To ignore some files, you can create a soft link from .gitignore to .dockerignore using ln:

      ln -s .gitignore .dockerignore
    • run yarn install and yarn run build

      The yarn run build command is equivalent to npx webpack --config webpack.config.js, which is the scripts set in package.json. Besides, move dependencies into devDependencies as follows:

      "name": "openapi-scripts",
      "devDependencies": {
      "webpack": "^5.74.0",
      "webpack-cli": "^4.10.0"
      "scripts": {},
      "dependencies": {
      "@apidevtools/json-schema-ref-parser": "^9.0.9",
      "commander": "^9.3.0",
      "openapi-snippet": "^0.14.0"
  • The second stage is a result stage, which builds a image for production.

Step 4. Build the Docker image

To build a image for testing, run the following command to build a test image:

$ docker build -t test .
[1/2] STEP 1/4: FROM node:16 AS build
[1/2] STEP 2/4: WORKDIR /build
--> 73bbc8c7552
[1/2] STEP 3/4: COPY . .
--> 53e13c02e1a
[1/2] STEP 4/4: RUN yarn install && yarn run build
yarn install v1.22.19
[1/4] Resolving packages...
[2/4] Fetching packages...
[3/4] Linking dependencies...
[4/4] Building fresh packages...
Done in 22.27s.
yarn run v1.22.19
$ webpack --config webpack.config.js
Done in 6.36s.
--> 5aa7f288822
[2/2] STEP 1/3: FROM node:16
[2/2] STEP 2/3: COPY --from=build /build/dist/main.js ./
--> 0c7bf448572
[2/2] STEP 3/3: ENTRYPOINT ["node", "main.js"]
[2/2] COMMIT test
--> 9dd21695569
Successfully tagged localhost/test:latest

Start a container with the test image and run the ls command to see files in container:

$ docker run -i -t --entrypoint bash 9dd2
root@007:/# ls -la
total 484
dr-xr-xr-x. 1 root root 28 Aug 6 06:43 .
dr-xr-xr-x. 1 root root 28 Aug 6 06:43 ..
drwxr-xr-x. 1 root root 179 Aug 2 01:26 bin
drwxr-xr-x. 2 root root 6 Mar 19 13:44 boot
drwxr-xr-x. 5 root root 360 Aug 6 06:43 dev
drwxr-xr-x. 1 root root 31 Aug 6 06:43 etc
drwxr-xr-x. 1 root root 18 Aug 2 04:21 home
drwxr-xr-x. 1 root root 42 Aug 2 01:26 lib
-rw-r--r--. 1 root root 495164 Aug 7 2022 main.js
drwxr-xr-x. 2 root root 6 Aug 1 00:00 media
drwxr-xr-x. 2 root root 6 Aug 1 00:00 mnt
drwxr-xr-x. 1 root root 27 Aug 2 04:24 opt
dr-xr-xr-x. 161 nobody nogroup 0 Aug 6 06:43 proc
drwx------. 1 root root 20 Aug 2 04:24 root
drwxr-xr-x. 1 root root 42 Aug 6 06:43 run
drwxr-xr-x. 1 root root 20 Aug 2 01:26 sbin
drwxr-xr-x. 2 root root 6 Aug 1 00:00 srv
dr-xr-xr-x. 12 nobody nogroup 0 Aug 5 00:14 sys
drwxrwxrwt. 1 root root 32 Aug 2 04:24 tmp
drwxr-xr-x. 1 root root 19 Aug 1 00:00 usr
drwxr-xr-x. 1 root root 17 Aug 1 00:00 var

It works!