Version 5 supported

Client-side build tooling

Core JavaScript, CSS, and thirdparty client-side dependencies are managed with the build tooling described below.

Note this only applies to core Silverstripe CMS dependencies, you're free to manage dependencies in your project codebase however you like.


The Node.js JavaScript runtime is the foundation of our client-side build tool chain. If you want to do things like upgrade dependencies, make changes to core JavaScript or SCSS files, you'll need Node installed on your dev environment.

We recommend using the Node Version Manager (nvm) to ensure you use the appropriate version of node.

If you're using nvm, make sure you use it to install and swap to the correct version of node before you run any of the yarn commands.

nvm install && nvm use

yarn is the package manager we use for JavaScript dependencies. You'll need to install yarn after Node.js is installed. See yarn installation docs. We recommend using npm which comes with Node.js to install it globally.

npm install -g yarn

Once you've installed Node.js and yarn, run the following command once in the silverstripe/admin module folder and in each module folder you are working on:

yarn install
The silverstripe/admin repository includes some components and dependencies that other modules need to work. Make sure that in addition to the module(s) who's code you're touching, you also run yarn install in the directory for silverstripe/admin.

You may need to first run composer reinstall silverstripe/admin --prefer-source if you installed that module without --prefer-source originally.

Build commands

The script property of a package.json file can be used to define command line scripts.

To run one of these scripts, open up your terminal, change to the directory where package.json is located, and run yarn <SCRIPT_NAME>. Where <SCRIPT_NAME> is the name of the script you wish to run.


During development, you'll want to build the core JavaScript and CSS files in development mode. This is faster than yarn build below and outputs the files in a format that is useful for debugging.

yarn dev

You might want to automatically rebuild whenever you change a .js or .scss file. This is useful for when you are rapidly making lots of small changes.

yarn watch

When you've finished making your changes, build the core JavaScript and CSS files in production mode. You will need to run this script before committing your changes to git.

yarn build

Build JavaScript or CSS separately

If you are only working on JavaScript or only working on CSS you might want to only build what you're working on. You can do this by adding WEBPACK_CHILD=css or WEBPACK_CHILD=js before the relevant yarn command, for example:

WEBPACK_CHILD=css yarn dev

The css or js portion of this is defined in the webpack.config.js file. Some modules may also include other configured components that can be built independently as well.

Lint and test

You can lint and run JavaScript unit tests manually - though note that these are also automatically run as part of the yarn build script. You will not be able to build production-ready distribution files if either of these fails.

yarn lint
yarn test

Requiring Silverstripe CMS JavaScript modules in your own CMS customisation

Silverstripe CMS creates bundles which contain many dependencies you might also want to use in your own CMS customisation (e.g. react). You might also need some of Silverstripe CMS's own JavaScript components (e.g. components/FormBuilder).

To avoid transpiling these into your own generated bundles, we have exposed many libraries as Webpack externals. This helps to keep the file size of your own bundle small, and avoids execution issues with multiple versions of the same library.

In order to find out which libraries are exposed, check the js/externals.js file in @silverstripe/webpack-config.

A shortened webpack.config.js in your own module could look as follows:

module.exports = {
  entry: {
    bundle: 'mymodule/client/src/js/bundle.js',
  output: {
    path: './client/dist',
    filename: 'js/[name].js',
  externals: {
    'components/FormBuilder/FormBuilder': 'FormBuilder',
    jQuery: 'jQuery',
    react: 'react',

Now you can use the following statements in your own code without including those dependencies in your generated bundle:

import react from 'react';
import jQuery from 'jQuery';
import FormBuilder from 'components/FormBuilder/FormBuilder';

For a more in-depth explanation of how to use @silverstripe/webpack-config take a look at the readme.