Description

Workspaces is a generic term that refers to the set of features in the npm cli that provides support to managing multiple packages from your local file system from within a singular top-level, root package.

This set of features makes up for a much more streamlined workflow handling linked packages from the local file system. Automating the linking process as part ofnpm install and avoiding manually having to usenpm link in order to add references to packages that should be symlinked into the currentnode_modules folder.

We also refer to these packages being auto-symlinked duringnpm install as a singleworkspace, meaning it's a nested package within the current local file system that is explicitly defined in thepackage.jsonworkspaces configuration.

Defining workspaces

Workspaces are usually defined via theworkspaces property of thepackage.json file, e.g:

{
"name":"my-workspaces-powered-project",
"workspaces":["packages/a"]
}

Given the abovepackage.json example living at a current working directory. that contains a folder namedpackages/a that itself contains apackage.json inside it, defining a Node.js package, e.g:

.
+-- package.json
`-- packages
   +-- a
|`-- package.json

The expected result once runningnpm install in this current working directory. is that the folderpackages/a will get symlinked to thenode_modules folder of the current working dir.

Below is a postnpm install example, given that same previous example structure of files and folders:

.
+-- node_modules
|`-- a ->../packages/a
+-- package-lock.json
+-- package.json
`-- packages
   +-- a
|   `-- package.json

Getting started with workspaces

You may automate the required steps to define a new workspace usingnpm init. For example in a project that already has apackage.json defined you can run:

This command will create the missing folders and a newpackage.json file (if needed) while also making sure to properly configure the"workspaces" property of your root projectpackage.json.

Adding dependencies to a workspace

It's possible to directly add/remove/update dependencies of your workspaces using theworkspace config.

For example, assuming the following structure:

.
+-- package.json
`-- packages
   +-- a
|`-- package.json
`-- b
`-- package.json

If you want to add a dependency namedabbrev from the registry as a dependency of your workspacea, you may use the workspace config to tell the npm installer that package should be added as a dependency of the provided workspace:

Note: other installing commands such asuninstall,ci, etc will also respect the providedworkspace configuration.

Using workspaces

Given thespecifities of how Node.js handles module resolution it's possible to consume any defined workspace by its declaredpackage.jsonname. Continuing from the example defined above, let's also create a Node.js script that will require the workspacea example module, e.g:

// ./packages/a/index.js
module.exports='a'
// ./lib/index.js
const moduleA= require('a')
console.log(moduleA) // -> a

When running it with:

node lib/index.js

This demonstrates how the nature ofnode_modules resolution allows forworkspaces to enable a portable workflow for requiring eachworkspace in such a way that is also easy topublish these nested workspaces to be consumed elsewhere.

Running commands in the context of workspaces

You can use theworkspace configuration option to run commands in the context of a configured workspace. Additionally, if your current directory is in a workspace, theworkspace configuration is implicitly set, andprefix is set to the root workspace.

Following is a quick example on how to use thenpm run command in the context of nested workspaces. For a project containing multiple workspaces, e.g:

.
+-- package.json
`-- packages
   +-- a
|`-- package.json
`-- b
`-- package.json

By running a command using theworkspace option, it's possible to run the given command in the context of that specific workspace. e.g:

You could also run the command within the workspace.

Either will run thetest script defined within the./packages/a/package.json file.

Please note that you can also specify this argument multiple times in the command-line in order to target multiple workspaces, e.g:

It's also possible to use theworkspaces (plural) configuration option to enable the same behavior but running that command in the context ofall configured workspaces. e.g:

Will run thetest script in both./packages/a and./packages/b.

Commands will be run in each workspace in the order they appear in yourpackage.json

{
"workspaces":["packages/a","packages/b"]
}

Order of run is different with:

{
"workspaces":["packages/b","packages/a"]
}

Ignoring missing scripts

It is not required for all of the workspaces to implement scripts run with thenpm run command.

By running the command with the--if-present flag, npm will ignore workspaces missing target script.

See also

• npm install
• npm publish
• npm run-script
• config

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1 contributorlukekarrys

Last edited bylukekarrys onOctober 26, 2022