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Web basics - package.json

The package.json file is auto-generated for you by the CLI, based on your answers to the prompts.

At the top you'll find the name and description of your application.

Following this, there are three key sections you need to be aware of:

  • config
  • scripts
  • dependencies


When running the app on your local machine, you can adjust a few settings under the config section, including which host to connect to and what port to run the dev server on.

"config": {
"API_HOST": "wss://dev-position2/gwf/",
"DEFAULT_USER": "JaneDee",
"PORT": 6060


The next section is scripts. Some have been auto-generated for you; feel free to add your own scripts, as needed.

These are the commands that you invoke with $ npm run - when you execute that command from your command line, node will look at the scripts listed here to know what to run. For example, $ npm run clean:dist will run node ../.build/clean.js dist.

  "scripts": {
"build": "npm run build:webpack",
"build:with-host": "cross-env API_HOST=$npm_package_config_API_HOST npm run build:webpack",
"build:webpack": "cross-env NODE_ENV=production AUTO_CONNECT=true webpack",
"clean": "npm run clean:dist",
"clean:dist": "node ../.build/clean.js dist",
"copy-files": "copyfiles -u 1 src/**/*.{css,scss,ttf} ./dist/esm",
"dev": "npm run dev:webpack",
"dev:webpack": "cross-env API_HOST=$npm_package_config_API_HOST AUTO_CONNECT=true DEFAULT_USER=$npm_package_config_DEFAULT_USER DEFAULT_PASSWORD=$npm_package_config_DEFAULT_PASSWORD NODE_ENV=development webpack serve --open",
"serve": "serve dist -p $npm_package_config_PORT",
"test": "echo \"Error: no test specified\""

Your settings from the config block are passed to different scripts as environment variables, using cross-env. So, for example, if you want to add a new config for a DEFAULT_VIEW:

  • add the config to the config block as "DEFAULT_VIEW": "reporting"
  • in the npm script that requires the variable, add DEFAULT_VIEW=$npm_package_config_DEFAULT_VIEW.


Last but not least, the dependencies section contains a list of your app's dependencies and their versions.


This includes @genesislcap dependencies. This is where you can change the dependency versions to upgrade to a newer version of the platform.

"dependencies": {
"@genesislcap/foundation-comms": <FoundationUi/>,
"@genesislcap/foundation-entity-management": <FoundationUi/>,
"@genesislcap/foundation-login": <FoundationUi/>,
"@genesislcap/foundation-utils": <FoundationUi/>,
"@genesislcap/foundation-zero": <FoundationUi/>,
"@genesislcap/foundation-ui": <FoundationUi/>,
"@microsoft/fast-components": "^2.16.6",
"@microsoft/fast-element": "^1.6.2",
"@microsoft/fast-foundation": "^2.27.1",
"@microsoft/fast-router": "^0.2.11",
"@microsoft/fast-web-utilities": "^5.0.1",
"rxjs": "^7.4.0",
"tslib": "^2.3.1"

You can use the lerna add command (instead of npm install) if you need to add more dependencies, because the app is a lerna-managed monorepo.


Do not use npm install to install packages as advised in the lerna documentation. It might work initially, but over time it can cause errors in the dependency tree and stop your application from building.

If you run into issues after running npm install, you should be able to recover by running $ npm run clean:all && npm run bootstrap. This will clear all dependency packages and download/link them again.

The devDependencies section is for dependencies that are only used in development - think of tools such as linters. These additional dependencies will not be added to the final production bundle and therefore will not increase the download size of the application to the user's browser.

  "devDependencies": {
"@babel/core": "^7.12.9",
"@typescript-eslint/eslint-plugin": "^5.2.0",
"camel-case": "^4.1.2",
"typescript": "^4.5.5",

Adding dependencies

lerna manages the dependencies across the different packages in the monorepo and will attempt to simplify the downloaded packages by only downloading a package version one time; it downloads the package version to the node_modules of the project root and then symlinks it across to the other node_modules directories in your other lerna modules. It also allows you to link local modules without having to publish them to npm first.

You can add dependencies straight into the package.json of one of your modules and then run the $ npm run bootstrap command from the package.json in your web root. lerna ensures the modules are downloaded and linked together.


It is good practice to clean the node_modules out before running a bootstrap, using $ npm run clean:all. You can run both commands in one, using $ npm run clean:all && npm run bootstrap.

Which package.json?

When first starting to work with the lerna-managed monorepo, there can be some confusion about which package.json you need to change. Usually, there are multiple package.json files spread across the project:

  • Each of your modules has its own package.json.
  • There is also a package.json at the root of the lerna project (the client root, in the /client directory in the apps created from the seed projects).

Some examples of changes you might make are:

  • Adding a dependency. As stated in the adding dependencies section, you should navigate to the package.json in the directory of the module that you want to add the dependency to. For example, if you want to add the dependency @genesislcap/foundation-login to your web app, you probably want to add the dependency to the client/web/package.json file. Alternatively, if you want to add the @genesislcap/foundation-comms dependency to a separate module that you are building in the same repository, add it to the package.json of that module.

  • Adding a module command. If you want to add a command that is specific to a module, such as a command to extract the API from a tsdoc comment, then edit the package.json specific to that package.

  • Adding a CI/workflow command. If you want to add a command to be run as part of CI or a workflow, such as during a git command, edit the file in your client root. For example, if you want to set up linting checks, add the linting command to the client/package.json file.


As a general rule, there are two categories of change. Understanding each one will help you understand which package.json you need to change. A module-level change, such as adding a dependency to an app or package in your app, requires you to update the package.json of that app or package. If you want to add a script or dependency to help manage your repository, this must go into your top-level package.json. This is a special package.json that only contains scripts and dependencies that you use during CI or developing locally; it won't contain any tools or dependencies that end users will interact with.

Example project

The following example shows a project that has two apps (a spot trading app and a derivatives trading app).

There are also two custom packages, one that is a theme that takes @genesislcap/foundation-ui and customises it, and one that is used for common calculations that are required across both the apps.

Some examples of changes for the project:

  • Set up linting in client/package.json, because you want to run linting checks across all parts of the code.
  • The "Blazer" theme requires @genesislcap/foundation-ui as a dependency so that it can import the web components and export them with customised css/theming. For this, add a dependency to client/packages/blazer/package.json.
  • The "Blazer" theme needs to be used in both apps to keep a consistent look and feel, and the calculations package is required in both apps too. Add these dependencies in the package.json of each module, and then lerna will ensure they're linked together. This means you can see the local changes without having to publish the theme or calculation package to npm.

If you need an external dependency to both apps, such as @microsoft/api-documenter, then lerna will only download it once in the common node_modules; it then symlinks it to where it is required.