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How To Use Custom webpack Configurations with Angular CLI Builder


This tutorial will teach you, step-by-step, how to use custom webpack configurations with Angular CLI Builder.

The Angular CLI can create a new Angular project and it will handle the webpack configuration. However, there are situations where you will want to add custom webpack functionality.

For the purposes of this article, you will learn how to use the [moment.js] library and remove unused locales to create a smaller bundle size.

Note: [moment.js] is a popular library for handling date and time. However, the current project status suggests that there may be other libraries with modern approaches that may suit your project better depending on your target audience. For educational purposes in reducing bundle sizes, this article will continue to use [moment.js].

In this article, you will take an existing Angular CLI-generated project and use [@angular-builders/custom-webpack] for a custom webpack configuration.


To complete this tutorial, you will need:

This tutorial was verified with Angular v10.2.0, [@angular-builders/custom-webpack] v10.0.1, [moment.js] v2.29.1, and [moment-locales-webpack-plugin] v1.2.0.

Step 1 — Setting Up the Project

In your terminal window, use the following command:

You can use [@angular/cli], found here, to create a new Angular Project.

$ npx @angular/cli new AngularCustomWebpackConfig --style=css --routing=false --skip-tests

This will configure a new Angular project with styles set to “CSS” (as opposed to “Sass”, “Less”, or “Stylus”), no routing, and skipping tests.

Navigate to the newly created project directory:

$ cd AngularCustomWebpackConfig

You can then install [moment.js] to your project and import this into your project:

$ npm install moment@2.29.1

To reduce the size of the [moment.js] library, you will need to also add [moment-locales-webpack-plugin] as a [devDependency]:

$ npm install --save-dev moment-locales-webpack-plugin@1.2.0

In order to use a custom webpack config, you will need to add [@angular-builders/custom-webpack] and [@angular-builders/dev-server] to your project as [devDependency] packages:

$ npm install --save-dev @angular-builders/custom-webpack@10.0.1

At this point you should have an Angular project generated by Angular CLI, [moment.js][moment-locales-webpack-plugin], and [@angular-builders/custom-webpack].

Step 2 — Building a Localized Clock Display

The example project for this article will display date and time information in French.

Open [app.component.ts] in your code editor and import moment and use it to display the current time in the format of the month name, day of the month, year, and time ([LLL]) using the French ([fr]) locale:

import { Component, OnInit } from '@angular/core';

import * as moment from 'moment';

  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
export class AppComponent implements OnInit {
  currentTimeFRLocale: string;

  ngOnInit(): void {
    this.currentTimeFRLocale = moment().format('LLL');

Then, open [app.component.html] in your code editor and use the [currentTimeFRLocale]:

<h1>{{ currentTimeFRLocale }}</h1>

This code will display the date and time string.

Run the application:

$ npm start

And open it in a browser:

Screenshot of Angular application displaying: 8 avril 2019 15:29

Once you verify that your application is working as expected, take a note of the values for [main.js] and [vendor.js] in the console;

Unmodified Webpack Outputchunk {main} main.js, (main) 15 kB [initial] [rendered]
chunk {vendor} vendor.js, (vendor) 3.04 MB [initial] [rendered]

The vendor file, which contains [moment.js], is 3.04 MB in size.

Step 3 — Modifying a Localized Clock Display with a Custom webpack Configuration

[moment.js] supports many locales by default. If the audience for your project does not require certain languages, removing the locales that are not necessary can help reduce file sizes. Smaller file sizes in turn will let your application load quicker for the end-user.

With your code editor, create a new [custom-webpack.config.js] file and add the following lines of code:

const MomentLocalesPlugin = require('moment-locales-webpack-plugin');

module.exports = {
  plugins: [
    new MomentLocalesPlugin({
      localesToKeep: ['fr']

This will require the [moment-locales-webpack-plugin] and use it to keep the [fr] locale – which will be date and time terms in the French language.

Next, you will need to modify [angular.json] to use this new configuration.

Open [angular.json] in your code editor. Inside of the [architect/build] object, update the [builder] from [@angular-devkit/build-angular:browser] to [@angular-builders/custom-webpack:browser] and add the [customWebpackConfig] key:

"architect": {
  "build": {
    "builder": "@angular-builders/custom-webpack:browser",
    "options": {
      "customWebpackConfig": {
        "path": "./custom-webpack.config.js",
        "replaceDuplicatePlugins": true
      // ...
    // ...
  // ...

This will build the application with the custom webpack configuration.

You will also want to apply the custom webpack configuration when developing locally.

Revisit the [angular.json] in your code editor. Inside of the [architect/serve] object, update the builder from [@angular-devkit/build-angular:dev-server] to [@angular-builders/custom-webpack:dev-server]:

"architect": {
  // ...
  "serve": {
    "builder": "@angular-builders/custom-webpack:dev-server",
    "options": {
      "browserTarget": "AngularCustomWebpackConfig:build"
    "configurations": {
      "production": {
        "browserTarget": "AngularCustomWebpackConfig:build:production"
  // ...

At this point, your application knows to use the [@angular-builders/custom-webpack] instead of [@angular-devkit/build-angular] and where to look for the custom webpack configuration.

Note: Previously, the [@angular-builders/dev-server] package was required. However, since version 8, it has been deprecated and [@angular-builders/custom-webpack:dev-server] should be used instead.

Run the application:

$ npm start

Once you verify that your application is working as expected, take note of the values for [main.js] and [vendor.js] in the console.

Looking back, the unmodified webpack configuration generated [main.js] and [vendor.js] with the following file sizes:

Unmodified Webpack Outputchunk {main} main.js, (main) 15 kB [initial] [rendered]
chunk {vendor} vendor.js, (vendor) 3.04 MB [initial] [rendered]

Now, with the customized webpack configuration, the [main.js] and [vendor.js] file sizes have been reduced:

Custom Webpack Outputchunk {main} main.js, (main) 9.91 kB [initial] [rendered]
chunk {vendor} vendor.js, (vendor) 2.55 MB [initial] [rendered]

That is a difference of 5 kB and 490 kB respectively.


In this article, you learned how to use custom webpack configurations with Angular CLI Builder

Why not check out our series of guides on setting up your server with CentOS 8:


Original Content by Paul Halliday and edited by the author of this post according to the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.


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