Good tools make application development quicker and easier to maintain than
if you did everything by hand.
The Angular CLI is a command line interface tool
that can create a project, add files, and perform a variety of ongoing development tasks such
as testing, bundling, and deployment.
The goal in this guide is to build and run a simple Angular
application in TypeScript, using the Angular CLI
while adhering to the Style Guide recommendations that
benefit every Angular project.
By the end of the chapter, you'll have a basic understanding of development with the CLI
and a foundation for both these documentation samples and for real world applications.
You need to set up your development environment before you can do anything.
Install Node.js® and npm
if they are not already on your machine.
Verify that you are running at least node 6.9.x and npm 3.x.x
by running node -v and npm -v in a terminal/console window.
Older versions produce errors, but newer versions are fine.
Generate a new project and skeleton application by running the following commands:
ng new my-app
Patience please.
It takes time to set up a new project, most of it spent installing npm packages.
Step 3: Serve the application
Go to the project directory and launch the server.
cd my-app
ng serve --open
The ng serve command launches the server, watches your files,
and rebuilds the app as you make changes to those files.
Using the --open (or just -o) option will automatically open your browser
on http://localhost:4200/.
Your app greets you with a message:
Step 4: Edit your first Angular component
The CLI created the first Angular component for you.
This is the root component and it is named app-root.
You can find it in ./src/app/app.component.ts.
Open the component file and change the title property from Welcome to app!! to Welcome to My First Angular App!!:
The browser reloads automatically with the revised title. That's nice, but it could look better.
Open src/app/app.component.css and give the component some style.
Looking good!
What's next?
That's about all you'd expect to do in a "Hello, World" app.
You're ready to take the Tour of Heroes Tutorial and build
a small application that demonstrates the great things you can build with Angular.
Or you can stick around a bit longer to learn about the files in your brand new project.
Project file review
An Angular CLI project is the foundation for both quick experiments and enterprise solutions.
The first file you should check out is README.md.
It has some basic information on how to use CLI commands.
Whenever you want to know more about how Angular CLI works make sure to visit
the Angular CLI repository and
Wiki.
Some of the generated files might be unfamiliar to you.
The src folder
Your app lives in the src folder.
All Angular components, templates, styles, images, and anything else your app needs go here.
Any files outside of this folder are meant to support building your app.
src
app
app.component.css
app.component.html
app.component.spec.ts
app.component.ts
app.module.ts
assets
.gitkeep
environments
environment.prod.ts
environment.ts
favicon.ico
index.html
main.ts
polyfills.ts
styles.css
test.ts
tsconfig.app.json
tsconfig.spec.json
File
Purpose
`app/app.component.{ts,html,css,spec.ts}`
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Defines the `AppComponent` along with an HTML template, CSS stylesheet, and a unit test.
It is the **root** component of what will become a tree of nested components
as the application evolves.
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`app/app.module.ts`
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Defines `AppModule`, the [root module](guide/bootstrapping "AppModule: the root module") that tells Angular how to assemble the application.
Right now it declares only the `AppComponent`.
Soon there will be more components to declare.
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`assets/*`
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A folder where you can put images and anything else to be copied wholesale
when you build your application.
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`environments/*`
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This folder contains one file for each of your destination environments,
each exporting simple configuration variables to use in your application.
The files are replaced on-the-fly when you build your app.
You might use a different API endpoint for development than you do for production
or maybe different analytics tokens.
You might even use some mock services.
Either way, the CLI has you covered.
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`favicon.ico`
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Every site wants to look good on the bookmark bar.
Get started with your very own Angular icon.
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`index.html`
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The main HTML page that is served when someone visits your site.
Most of the time you'll never need to edit it.
The CLI automatically adds all `js` and `css` files when building your app so you
never need to add any `<script>` or `<link>` tags here manually.
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`main.ts`
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The main entry point for your app.
Compiles the application with the [JIT compiler](guide/glossary#jit)
and bootstraps the application's root module (`AppModule`) to run in the browser.
You can also use the [AOT compiler](guide/glossary#ahead-of-time-aot-compilation)
without changing any code by passing in `--aot` to `ng build` or `ng serve`.
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`polyfills.ts`
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Different browsers have different levels of support of the web standards.
Polyfills help normalize those differences.
You should be pretty safe with `core-js` and `zone.js`, but be sure to check out
the [Browser Support guide](guide/browser-support) for more information.
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`styles.css`
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Your global styles go here.
Most of the time you'll want to have local styles in your components for easier maintenance,
but styles that affect all of your app need to be in a central place.
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`test.ts`
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This is the main entry point for your unit tests.
It has some custom configuration that might be unfamiliar, but it's not something you'll
need to edit.
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`tsconfig.{app|spec}.json`
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TypeScript compiler configuration for the Angular app (`tsconfig.app.json`)
and for the unit tests (`tsconfig.spec.json`).
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The root folder
The src/ folder is just one of the items inside the project's root folder.
Other files help you build, test, maintain, document, and deploy the app.
These files go in the root folder next to src/.
my-app
e2e
app.e2e-spec.ts
app.po.ts
tsconfig.e2e.json
node_modules/...
src/...
.angular-cli.json
.editorconfig
.gitignore
karma.conf.js
package.json
protractor.conf.js
README.md
tsconfig.json
tslint.json
File
Purpose
`e2e/`
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Inside `e2e/` live the End-to-End tests.
They shouldn't be inside `src/` because e2e tests are really a separate app that
just so happens to test your main app.
That's also why they have their own `tsconfig.e2e.json`.
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`node_modules/`
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`Node.js` creates this folder and puts all third party modules listed in
`package.json` inside of it.
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`.angular-cli.json`
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Configuration for Angular CLI.
In this file you can set several defaults and also configure what files are included
when your project is build.
Check out the official documentation if you want to know more.
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`.editorconfig`
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Simple configuration for your editor to make sure everyone that uses your project
has the same basic configuration.
Most editors support an `.editorconfig` file.
See http://editorconfig.org for more information.
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`.gitignore`
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Git configuration to make sure autogenerated files are not commited to source control.
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`karma.conf.js`
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Unit test configuration for the [Karma test runner](https://karma-runner.github.io),
used when running `ng test`.
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`package.json`
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`npm` configuration listing the third party packages your project uses.
You can also add your own [custom scripts](https://docs.npmjs.com/misc/scripts) here.
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`protractor.conf.js`
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End-to-end test configuration for [Protractor](http://www.protractortest.org/),
used when running `ng e2e`.
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`README.md`
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Basic documentation for your project, pre-filled with CLI command information.
Make sure to enhance it with project documentation so that anyone
checking out the repo can build your app!
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`tsconfig.json`
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TypeScript compiler configuration for your IDE to pick up and give you helpful tooling.
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`tslint.json`
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Linting configuration for [TSLint](https://palantir.github.io/tslint/) together with
[Codelyzer](http://codelyzer.com/), used when running `ng lint`.
Linting helps keep your code style consistent.
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Next Step
If you're new to Angular, continue with the
tutorial.
You can skip the "Setup" step since you're already using the Angular CLI setup.
