angular-cn/aio/content/guide/npm-packages.md

Workspace npm dependencies

The Angular Framework, Angular CLI, and components used by Angular applicatins are packaged as npm packages and distributed via the npm registry.

You can download and install these npm packages by using the npm CLI client, which is installed with and runs as a Node.js® application. By default, the Angular CLI uses the npm client.

Alternatively, you can use the yarn client for downloading and installing npm packages.

See Getting Started for information about the required versions and installation of Node.js and npm.

If you already have projects running on your machine that use other versions of Node.js and npm, consider using nvm to manage the multiple versions of Node.js and npm.

package.json

Both npm and yarn install the packages that are identified in a package.json file.

The CLI command ng new creates a package.json file when it creates the new workspace. This package.json is used by all projects in the workspace, including the initial app project that is created by the CLI when it creates the workspace.

Initially, this package.json includes a starter set of packages, some of which are required by Angular and others that support common application scenarios. You add packages to package.json as your application evolves. You may even remove some.

The package.json is organized into two groups of packages:

• Dependencies are essential to running applications.
• DevDependencies are only necessary to develop applications.

Library developers: By default, the CLI command ng generate library creates a package.json for the new library. That package.json is used when publishing the library to npm. For more information, see the CLI wiki page Library Support.

{@a dependencies}

Dependencies

The packages listed in the dependencies section of package.json are essential to running applications.

The dependencies section of package.json contains:

• Angular packages: Angular core and optional modules; their package names begin @angular/.

• Support packages: 3rd party libraries that must be present for Angular apps to run.

• Polyfill packages: Polyfills plug gaps in a browser's JavaScript implementation.

To add a new dependency, use the ng add command.

{@a angular-packages}

Angular packages

The following Angular packages are included as dependencies in the default package.json file for a new Angular workspace. For a complete list of Angular packages, see the API reference.

Package name	Description
@angular/animations	Angular's animations library makes it easy to define and apply animation effects such as page and list transitions. For more information, see the Animations guide.
@angular/common	The commonly-needed services, pipes, and directives provided by the Angular team. The HttpClientModule is also here, in the @angular/common/http subfolder. For more information, see the HttpClient guide.
@angular/compiler	Angular's template compiler. It understands templates and can convert them to code that makes the application run and render. Typically you don’t interact with the compiler directly; rather, you use it indirectly via platform-browser-dynamic when JIT compiling in the browser. For more information, see the Ahead-of-time Compilation guide.
@angular/core	Critical runtime parts of the framework that are needed by every application. Includes all metadata decorators, Component, Directive, dependency injection, and the component lifecycle hooks.
@angular/forms	Support for both template-driven and reactive forms. For information about choosing the best forms approach for your app, see Introduction to forms.
@angular/http	Angular's legacy HTTP client, which was deprecated in version 5.0 in favor of @angular/common/http.
@angular/ platform‑browser	Everything DOM and browser related, especially the pieces that help render into the DOM. This package also includes the bootstrapModuleFactory() method for bootstrapping applications for production builds that pre-compile with AOT.
@angular/ platform‑browser‑dynamic	Includes providers and methods to compile and run the app on the client using the JIT compiler.
@angular/router	The router module navigates among your app pages when the browser URL changes. For more information, see Routing and Navigation.

{@a support-packages}

Support packages

The following support packages are included as dependencies in the default package.json file for a new Angular workspace.

Package name	Description
rxjs	Many Angular APIs return observables. RxJS is an implementation of the proposed Observables specification currently before the TC39 committee, which determines standards for the JavaScript language.
zone.js	Angular relies on zone.js to run Angular's change detection processes when native JavaScript operations raise events. Zone.js is an implementation of a specification currently before the TC39 committee that determines standards for the JavaScript language.

{@a polyfills}

Polyfill packages

Many browsers lack native support for some features in the latest HTML standards, features that Angular requires. Polyfills can emulate the missing features. The Browser Support guide explains which browsers need polyfills and how you can add them.

The package.json for a new Angular workspace installs the core-js package, which polyfills missing features for several popular browser.

{@a dev-dependencies}

DevDependencies

The packages listed in the devDependencies section of package.json help you develop the application on your local machine. You don't deploy them with the production application.

To add a new devDependency, use either one of the following commands:

npm install --dev <package-name> yarn add --dev <package-name>

The following devDependencies are provided in the default package.json file for a new Angular workspace.

Package name	Description
@angular‑devkit/ build‑angular	The Angular build tools.
@angular/cli	The Angular CLI tools.
@angular/ compiler‑cli	The Angular compiler, which is invoked by the Angular CLI's ng build and ng serve commands.
@angular/ language‑service	The Angular language service analyzes component templates and provides type and error information that TypeScript-aware editors can use to improve the developer's experience. For example, see the Angular language service extension for VS Code.
**@types/... **	TypeScript definition files for 3rd party libraries such as Jasmine and Node.js.
codelyzer	A linter for Angular apps whose rules conform to the Angular style guide.
**jasmine/... **	Packages to support the Jasmine test library.
**karma/... **	Packages to support the karma test runner.
protractor	An end-to-end (e2e) framework for Angular apps. Built on top of WebDriverJS.
ts-node	TypeScript execution environment and REPL for Node.js.
tslint	A static analysis tool that checks TypeScript code for readability, maintainability, and functionality errors.
typescript	The TypeScript language server, including the tsc TypeScript compiler.

Related information

For information about how the Angular CLI handles packages see the following guides:

• Building and serving describes how packages come together to create a development build.
• Deployment describes how packages come together to create a production build.