docs(npm-packages): edit copy to guidelines (#3361)
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Kapunahele Wong
Jules Kremer
parent
a6478bcc9d
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66562c8710
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@ -5,133 +5,139 @@ include ../_util-fns
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These packages are maintained and installed with the Node Package Manager (<a href="https://docs.npmjs.com/" target="_blank">npm</a>).
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.l-sub-section
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:marked
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Node.js and npm are essential to Angular development.
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Node.js and npm are essential to Angular development.
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<a href="https://docs.npmjs.com/getting-started/installing-node" target="_blank" title="Installing Node.js and updating npm">
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Get them now</a> if they're not already installed on your machine.
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**Verify that you are running node `v4.x.x` or higher and npm `3.x.x` or higher**
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by running the commands `node -v` and `npm -v` in a terminal/console window.
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Older versions produce errors.
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We recommend [nvm](https://github.com/creationix/nvm) for managing multiple versions of node and npm. You may need [nvm](https://github.com/creationix/nvm) if you already have projects running on your machine that use other versions of node and npm.
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Consider using [nvm](https://github.com/creationix/nvm) for managing multiple
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versions of node and npm. You may need [nvm](https://github.com/creationix/nvm) if
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you already have projects running on your machine that use other versions of node and npm.
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:marked
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We recommend a comprehensive starter-set of packages as specified in the `dependencies` and `devDependencies`
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sections of the <a href="https://docs.npmjs.com/files/package.json" target="_blank">package.json</a> file
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installed as described during [Setup](setup.html).
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:marked
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You can use other packages but we recommend *this particular set* to start with because (a) they work well together and
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(b) they include everything you'll need to build and run the sample applications in this series.
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During [Setup](setup.html), a <a href="https://docs.npmjs.com/files/package.json" target="_blank">package.json</a>
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file is installed with a comprehensive starter set of
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packages as specified in the `dependencies` and `devDependencies` sections.
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You can use other packages but the packages in _this particular set_ work well together and include
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everything you need to build and run the sample applications in this series.
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.l-sub-section
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:marked
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Note: A cookbook or guide page may require an additional library such as *jQuery*.
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:marked
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You'll install more than you need for QuickStart.
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No worries!
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You'll install more than you need for the QuickStart guide.
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No worries!
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You only serve to the client those packages that the application actually requests.
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This page explains what each package does. You can make substitutions later to suit your tastes and experience.
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.l-main-section
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:marked
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## *dependencies* and *devDependencies*
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The `package.json` includes two sets of packages,
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The `package.json` includes two sets of packages,
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[dependencies](#dependencies) and [devDependencies](#dev-dependencies).
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The *dependencies* are essential to *running* the application.
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The *devDependencies* are only necessary to *develop* the application.
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The *dependencies* are essential to *running* the application.
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The *devDependencies* are only necessary to *develop* the application.
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You can exclude them from production installations by adding `--production` to the install command, as follows:
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code-example(format="." language="bash").
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npm install my-application --production
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a(id="dependencies")
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.l-main-section
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:marked
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## *dependencies*
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The `dependencies` section of `package.json` contains:
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* ***Features*** - Feature packages give the application framework and utility capabilities.
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* ***Polyfills*** - Polyfills plug gaps in the browser's JavaScript implementation.
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* ***Other*** - Other libraries that support the application such as `bootstrap` for HTML widgets and styling.
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* ***Features***: Feature packages give the application framework and utility capabilities.
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* ***Polyfills***: Polyfills plug gaps in the browser's JavaScript implementation.
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* ***Other***: Other libraries that support the application such as `bootstrap` for HTML widgets and styling.
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.l-main-section
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:marked
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### Feature Packages
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***@angular/core*** - Critical runtime parts of the framework needed by every application.
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***@angular/core***: Critical runtime parts of the framework needed by every application.
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Includes all metadata decorators, `Component`, `Directive`, dependency injection, and the component lifecycle hooks.
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***@angular/common*** - The commonly needed services, pipes, and directives provided by the Angular team.
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***@angular/compiler*** - Angular's *Template Compiler*.
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It understands templates and can convert them to code that makes the application run and render.
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***@angular/common***: The commonly needed services, pipes, and directives provided by the Angular team.
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***@angular/compiler***: Angular's *Template Compiler*.
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It understands templates and can convert them to code that makes the application run and render.
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Typically you don’t interact with the compiler directly; rather, you use it indirectly via `platform-browser-dynamic` or the offline template compiler.
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***@angular/platform-browser*** - Everything DOM and browser related, especially the pieces that help render into DOM.
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This package also includes the bootstrapStatic method for bootstrapping applications for production builds that pre-compile templates offline.
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***@angular/platform-browser-dynamic*** - Includes [Providers](../api/core/index/Provider-type-alias.html) and a [bootstrap](ngmodule.html#bootstrap) method for applications that
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***@angular/platform-browser***: Everything DOM and browser related, especially
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the pieces that help render into the DOM.
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This package also includes the `bootstrapStatic()` method
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for bootstrapping applications for production builds that pre-compile templates offline.
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***@angular/platform-browser-dynamic***: Includes [Providers](../api/core/index/Provider-type-alias.html)
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and a [bootstrap](ngmodule.html#bootstrap) method for applications that
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compile templates on the client. Don’t use offline compilation.
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Use this package for bootstrapping during development and for bootstrapping plunker samples.
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***@angular/http*** - Angular's http client.
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***@angular/router*** - Component router.
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***@angular/upgrade*** - Set of utilities for upgrading AngularJS applications to Angular.
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***[system.js](https://github.com/systemjs/systemjs)*** - A dynamic module loader compatible with the
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***@angular/http***: Angular's HTTP client.
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***@angular/router***: Component router.
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***@angular/upgrade***: Set of utilities for upgrading AngularJS applications to Angular.
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***[system.js](https://github.com/systemjs/systemjs)***: A dynamic module loader compatible with the
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[ES2015 module](http://www.2ality.com/2014/09/es6-modules-final.html) specification.
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Other viable choices include the well-regarded [webpack](https://webpack.github.io/).
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Your future applications are likely to require additional packages that provide
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HTML controls, themes, data access, and various utilities.
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a(id="polyfills")
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.l-main-section
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:marked
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### Polyfill packages
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Angular requires certain [polyfills](https://en.wikipedia.org/wiki/Polyfill) in the application environment.
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Install these polyfills using the npm packages that Angular lists in the *peerDependencies* section of its `package.json`.
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You must list these packages in the `dependencies` section of your own `package.json`.
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.l-sub-section
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:marked
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For background on this requirement, see [Why peerDependencies?](#why-peer-dependencies).
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:marked
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***core-js*** - Patches the global context (window) with essential features of ES2015 (ES6).
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You may substitute an alternative polyfill that provides the same core APIs.
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***core-js***: Patches the global context (window) with essential features of ES2015 (ES6).
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You may substitute an alternative polyfill that provides the same core APIs.
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When these APIs are implemented by the major browsers, this dependency will become unnecessary.
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***rxjs*** - A polyfill for the [Observables specification](https://github.com/zenparsing/es-observable) currently before the
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***rxjs***: A polyfill for the [Observables specification](https://github.com/zenparsing/es-observable) currently before the
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[TC39](http://www.ecma-international.org/memento/TC39.htm) committee that determines standards for the JavaScript language.
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You can pick a preferred version of *rxjs* (within a compatible version range)
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You can pick a preferred version of *rxjs* (within a compatible version range)
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without waiting for Angular updates.
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***zone.js*** - A polyfill for the [Zone specification](https://gist.github.com/mhevery/63fdcdf7c65886051d55) currently before the
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***zone.js***: A polyfill for the [Zone specification](https://gist.github.com/mhevery/63fdcdf7c65886051d55) currently before the
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[TC39](http://www.ecma-international.org/memento/TC39.htm) committee that determines standards for the JavaScript language.
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You can pick a preferred version of *zone.js* to use (within a compatible version range)
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You can pick a preferred version of *zone.js* to use (within a compatible version range)
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without waiting for Angular updates.
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a(id="other")
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.l-main-section
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:marked
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### Other helper libraries
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***angular-in-memory-web-api*** - An Angular-supported library that simulates a remote server's web api
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without requiring an actual server or real http calls.
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Good for demos, samples, and early stage development (before we even have a server).
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Read about it in the [Http Client](server-communication.html#appendix-tour-of-heroes-in-memory-server) page.
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***bootstrap*** - [Bootstrap](http://getbootstrap.com/) is a popular HTML and CSS framework for designing responsive web apps.
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***angular-in-memory-web-api***: An Angular-supported library that simulates a remote server's web api
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without requiring an actual server or real HTTP calls.
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Good for demos, samples, and early stage development (before you even have a server).
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Read about it in the [HTTP Client](server-communication.html#in-mem-web-api) page.
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***bootstrap***: [Bootstrap](http://getbootstrap.com/) is a popular HTML and CSS framework for designing responsive web apps.
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Some of the samples improve their appearance with *bootstrap*.
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a(id="dev-dependencies")
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.l-main-section
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:marked
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@ -139,81 +145,80 @@ a(id="dev-dependencies")
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The packages listed in the *devDependencies* section of the `package.json` help you develop the application.
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You don't have to deploy them with the production application although there is no harm in doing so.
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***[concurrently](https://www.npmjs.com/package/concurrently)*** -
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***[concurrently](https://www.npmjs.com/package/concurrently)***:
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A utility to run multiple *npm* commands concurrently on OS/X, Windows, and Linux operating systems.
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***[lite-server](https://www.npmjs.com/package/lite-server)*** -
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A light-weight, static file server, by [John Papa](http://johnpapa.net/)
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***[lite-server](https://www.npmjs.com/package/lite-server)***:
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A light-weight, static file server, by [John Papa](http://johnpapa.net/)
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with excellent support for Angular apps that use routing.
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***[typescript](https://www.npmjs.com/package/typescript)*** -
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***[typescript](https://www.npmjs.com/package/typescript)***:
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the TypeScript language server, including the *tsc* TypeScript compiler.
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***@types/\**** - TypeScript definition files.
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Learn more about it in the [TypeScript Configuration](typescript-configuration.html#typings) chapter.
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***@types/\****: TypeScript definition files.
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Learn more about it in the [TypeScript Configuration](typescript-configuration.html#typings) guide.
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.l-main-section
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a(id="why-peer-dependencies")
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:marked
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## Why *peerDependencies*?
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There isn't a *peerDependencies* section in the QuickStart `package.json`.
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But Angular has a *peerDependencies* section in
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*its* package.json, which has important consequences for your application.
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It explains why you load the [polyfill](#polyfills) *dependency* packages in the QuickStart `package.json`,
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There isn't a [*peerDependencies*](https://nodejs.org/en/blog/npm/peer-dependencies/) section in the QuickStart `package.json`.
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But Angular has a *peerDependencies* section in
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*its* `package.json`, which has important consequences for your application.
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This section explains why you load the [polyfill](#polyfills) *dependency*
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packages in the QuickStart application's `package.json`,
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and why you'll need those packages in your own applications.
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An explanation of [peer dependencies](https://nodejs.org/en/blog/npm/peer-dependencies/) follows.
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Packages depend on other packages. For example, your application depends on the Angular package.
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Two packages, "A" and "B", could depend on the same third package "C".
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Two packages, "A" and "B", could depend on the same third package "C".
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"A" and "B" might both list "C" among their *dependencies*.
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What if "A" and "B" depend on different versions of "C" ("C1" and "C2"). The npm package system supports that.
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What if "A" and "B" depend on different versions of "C" ("C1" and "C2"). The npm package system supports that.
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It installs "C1" in the `node_modules` folder for "A" and "C2" in the `node_modules` folder for "B".
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Now "A" and "B" have their own copies of "C" and they run without interferring with one another.
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But there is a problem. Package "A" may require the presence of "C1" without actually calling upon it directly.
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"A" may only work if *everyone is using "C1"*. It falls down if any part of the application relies on "C2".
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The solution is for "A" to declare that "C1" is a *peer dependency*.
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The difference between a `dependency` and a `peerDependency` is roughly this:
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>A **dependency** says, "I need this thing directly available to *me*."
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>
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>A **peerDependency** says, "If you want to use me, you need this thing available to *you*."
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The Angular `package.json` specifies several *peer dependency* packages,
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The Angular `package.json` specifies several *peer dependency* packages,
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each pinned to a particular version of a third-party package.
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### We must install Angular's *peerDependencies* ourselves.
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### You must install Angular's *peerDependencies* yourself.
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When *npm* installs packages listed in *your* `dependencies` section,
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it also installs the packages listed within *their* packages `dependencies` sections.
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The process is recursive.
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However, as of version 3, *npm* does *not* install packages listed in *peerDependencies* sections.
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This means that when your application installs Angular, ***npm* doesn't automatically install
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the packages listed in Angular's *peerDependencies* section**.
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Fortunately, *npm* issues a warning (a) When any *peer dependencies* are missing, or (b)
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When the application or any of its other dependencies
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installs a different version of a *peer dependency*.
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installs a different version of a *peer dependency*.
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These warnings guard against accidental failures due to version mismatches.
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They leave you in control of package and version resolution.
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It is your responsibility to list all *peer dependency* packages **among your own *devDependencies***.
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.l-sub-section
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:marked
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#### The future of *peerDependencies*
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The Angular polyfill dependencies are hard requirements. Currently, there is no way to make them optional.
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However, there is an npm feature request for "optional peerDependencies," which would allow you to model this relationship better.
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However, there is an npm feature request for "optional peerDependencies," which would allow you to model this relationship better.
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When this feature request is implemented, Angular will switch from *peerDependencies* to *optionalPeerDependencies* for all polyfills.
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