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Nx CLI

The Nx CLI is a command-line interface tool that helps you setup, develop, build, and maintain applications. It provides commands for:

  • Generating new applications, and libraries with recommended defaults.
  • Running a development webserver that rebuilds your app on changes.
  • Generating a dependency graph for your application.
  • Building, and running unit and E2E test for apps, and libraries affected by your changes.
  • Formatting your source code to modern standards.
  • ...

Nx CLI and Angular CLI

Nx is not a replacement for Angular CLI. Under the hood, Nx uses the Angular CLI to generate code and run tasks.

When you run nx build myapp, Nx will invoke ng build myapp under the hood. When you run nx g component mycmp, Nx will invoke ng g component mycmp under the hood.

When it comes to generating code and running tasks, since nx delegates to ng, both CLIs will always produce the same result, except that running nx will often be a lot faster.

How?

Nx CLI uses advanced code analysis and computation caching to reuse previous computation results when possible. The Angular CLI doesn't do it. In other words, use nx instead of ng: everything will work just the same but often much faster.

The Nx CLI also supports a lot more commands than the Angular CLI. It can run a target against many projects in parallel, run a target against a project and its dependencies, etc..

Installing the CLI

Install the Nx CLI globally on your system using your preferred package manager:

Using npm:

npm install -g @nrwl/cli

Using yarn:

yarn global add @nrwl/cli

After that, you will have an nx executable you can use to run commands in your workspace.

If you don't have the Nx CLI installed globally, you can invoke nx using yarn nx and npm run nx.

Help and List

nx help will print a short description of every command. You can also pass --help to a command to see the available options (e.g., nx affected --help).

nx list will print the list of installed plugins and the list of plugins you can install. You can also pass a plugin name to it (e.g., nx list @nrwl/angular) to learn more about what the capabilities of that plugin.

Generating Code

The Nx CLI has an advanced code generator. With it, you can generate new applications, libraries, components, state management utilities. You can change existing applications. And, because the Nx CLI comes with an implementation of a virtual file system, you can preview the changes without affecting anything on disk.

The code generation recipes are called schematics. Schematics provide the underlying APIs for scaffolding, and utilities to automate changes to your filesystem. The example below is the command to generate a new application.

nx generate @nrwl/angular:application myapp

The @nrwl/angular package contains a collection of schematics, with application being the one used in this example. The Nx CLI applies the schematic to your workspace, verifying that the provided options are valid, and the destination files don't already exist. Once the validations are passed, the new files are generated, or existing files are updated. You can also customize the output of the generated application, by passing options to the schematic.

nx generate @nrwl/angular:application myapp --style=scss

You can preview the changes a schematic makes by using the --dry-run option. It will output the potential files created, and/or updated during the execution of the schematic.

Generate command:

nx generate runs schematics to create or modify code given some inputs from the developer.

  • nx generate
    Syntax: nx generate [plugin]:[schematic-name] [options]
    Example: nx generate @nrwl/angular:component mycmp --project=myapp

Running Tasks

The Nx CLI uses builders to perform tasks, such as building and bundling your application, running unit tests, or running E2E tests against a specific target, whether that be an application or workspace.

A builder is a function that uses the Architect API to perform a complex process such as "build", "test", or "lint".

You can configure the builders in angular.json.

{
  "projects": {
    "todos": {
      "root": "apps/todos/",
      "sourceRoot": "apps/todos/src",
      "projectType": "application",
      "architect": {
        "serve": {
          "builder": "@nrwl/web:dev-server",
          "options": {
            "buildTarget": "todos:build",
            "proxyConfig": "apps/todos/proxy.conf.json"
          },
          "configurations": {
            "production": {
              "buildTarget": "todos:build:production"
            }
          }
        },
        "test": {
          "builder": "@nrwl/jest:jest",
          "options": {
            "jestConfig": "apps/todos/jest.config.js",
            "tsConfig": "apps/todos/tsconfig.spec.json",
            "setupFile": "apps/todos/src/test-setup.ts"
          }
        }
      }
    }
  }
}

In the example above, the todos application has two targets: serve and test. The serve target uses the @nrwl/web:dev-server builder, and the test target uses @nrwl/jest:jest. Every target uses a builder which actually runs this target. So targets are analogous to typed npm scripts, and builders are analogous to typed shell scripts.

You can run the target as follows:

nx run todos:serve
nx run todos:test

A target can have multiple configuration. In the example above the serve target has two configurations: default and production.

nx run todos:serve # default configuration
nx run todos:serve:production # producttion configuration

Because running target is such a common operation, you can also use the following syntax to do it:

nx serve todos
nx serve todos --configuration=production
nx serve todos --prod

You can name your targets any way you want, define as many of them as you want, and use any builders you want to implement them.

These are some common targets:

  • nx build
    Syntax: nx build [project]
    Long form: nx run [project]:build
    Example: nx build my-app
  • nx lint
    Syntax: nx lint [project]
    Long form: nx run [project]:lint
    Example: nx lint my-app
  • nx serve
    Syntax: nx serve [project]
    Long form: nx run [project]:serve
    Example: nx serve my-app
  • nx e2e
    Syntax: nx e2e [project]
    Long form: nx run [project]:e2e
    Example: nx e2e my-app
  • nx test
    Syntax: nx test [project]
    Long form: nx run [project]:test
    Example: nx test my-app

Running Tasks for Multiple Projects

Nx allows you to run tasks across multiple projects.

Run-Many

Run the same target for all projects.

nx run-many --target=build --all

Run the same target for all projects in parallel.

nx run-many --target=build --all --parallel --maxParallel=8

Run the same target for selected projects.

nx run-many --target=build --projects=app1,app2

Run the same target for selected projects and their deps.

nx run-many --target=build --projects=app1,app2 --with-deps

Run the same target for the projects that failed last time.

nx run-many --target=build --all --only-failed

Any flags you pass to run-many that aren't Nx specific will be passed down to the builder.

nx run-many --target=build --all --prod

Affected

Run the same target for all the projects by the current code change (e.g., current Git branch).

nx affected --target=build

Same but in parallel.

nx affected --target=build --parallel --maxParallel=8

By default, the current code change is defined as a diff between master and HEAD. You can change it as follows:

nx affected --target=build --parallel --maxParallel=8 --base=origin/development --head=$CI_BRANCH_NAME

Running affected commands is very common, so Nx comes with a few shortcuts.

nx affected:build
nx affected:test
nx affected:lint
nx affected:e2e

Any flags you pass to run-many that aren't Nx specific will be passed down to the builder.

nx affected --target=build --prod

Other Commands

nx print-affected prints information about affected projects in the workspace.

nx dep-graph launches a visual graph of the dependencies between your projects.

nx affected:dep-graph launches the dependency graph with all affected projects highlighted.

nx list lists all installed and available plugins.

nx report prints basic information about the plugins used

nx format:write formats your code

nx format:check checks that your code is formatted