Run Tasks

In a monorepo setup, you don't just run tasks for a single project; you might have hundreds to manage. To help with this, Nx provides a powerful task runner that allows you to:

easily run multiple targets for multiple projects in parallel
define task pipelines to run tasks in the correct order
only run tasks for projects affected by a given change
speed up task execution with caching

Defining Tasks

Nx tasks can be created from existing package.json scripts, inferred from tooling configuration files, or defined in a project.json file. Nx combines these three sources to determine the tasks for a particular project.

{
  "name": "mylib",
  "scripts": {
    "build": "tsc -p tsconfig.lib.json",
    "test": "jest"
  }
}

The project configuration docs has the details for all the available configuration options.

Running Tasks

Nx uses the following syntax:

Syntax for Running Tasks in Nx

Run a Single Task

To run the test task for the header project run this command:

❯

npx nx test header

Run Tasks for Multiple Projects

You can use the run-many command to run a task for multiple projects. Here are a couple of examples.

Run the build task for all projects in the repo:

❯

npx nx run-many -t build

Run the build, lint and test task for all projects in the repo:

❯

npx nx run-many -t build lint test

Run the build, lint, and test tasks only on the header and footer projects:

❯

npx nx run-many -t build lint test -p header footer

Nx parallelizes these tasks, ensuring they run in the correct order based on their dependencies and task pipeline configuration. You can also control how many tasks run in parallel at once.

Learn more about the run-many command.

Run Tasks on Projects Affected by a PR

You can also run a command for all the projects affected by your PR like this:

❯

npx nx affected -t test

Learn more about the affected command here.

Defining a Task Pipeline

It is pretty common to have dependencies between tasks, requiring one task to be run before another. For example, you might want to run the build target on the header project before running the build target on the app project.

Nx can automatically detect the dependencies between projects (see project graph).

However, you need to specify for which targets this ordering is important. In the following example we are telling Nx that before running the build target it needs to run the build target on all the projects the current project depends on:

nx.json
{
  ...
  "targetDefaults": {
    "build": {
      "dependsOn": ["^build"]
    }
  }
}

This means that if we run nx build myreactapp, Nx will first execute build on modules-shared-ui and modules-products before running build on myreactapp.

You can define these task dependencies globally for your workspace in nx.json or individually in each project's project.json file.

Learn more about:

Reduce repetitive configuration

Learn more about leveraging targetDefaults to reduce repetitive configuration in the dedicated recipe.

Run Root-Level Tasks

Sometimes, you need tasks that apply to the entire codebase rather than a single project. To still benefit from caching, you can run these tasks through the "Nx pipeline". Define them in the root-level package.json or project.json as follows:

package.json
{
  "name": "myorg",
  "scripts": {
    "docs": "node ./generateDocsSite.js"
  },
  "nx": {}
}

Note the nx: {} property on the package.json. This is necessary to inform Nx about this root-level project. The property can also be expanded to specify cache inputs and outputs.

If you want Nx to cache the task, but prefer to use npm (or pnpm/yarn) to run the script (i.e. npm run docs) you can use the nx exec command:

package.json
{
  "name": "myorg",
  "scripts": {
    "docs": "nx exec -- node ./generateDocsSite.js"
  },
  "nx": {}
}

To invoke the task, use:

❯

npx nx docs

Learn more about root-level tasks on our dedicated recipe page.

Migration