240 lines
10 KiB
Markdown
240 lines
10 KiB
Markdown
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---
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title: Angular 2 Starter Project
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localeTitle: Angular 2 Starter Project
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---
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Este tutorial construirá un proyecto semilla extremadamente simple con Angular2. Comenzaremos con la aplicación más básica posible y luego agregaremos un poco más de funcionalidad.
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## Visión de conjunto
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Las aplicaciones de Angular 2 se crean mediante la creación de plantillas HTML que contienen marcas específicas angulares. Luego se crean clases para administrar las plantillas y todo se envuelve en un módulo, que se unen para crear su aplicación. Estos módulos se conocen como **componentes** .
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Angular interpreta estos módulos y los utiliza para presentar su aplicación en el navegador.
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## Aplicación de arranque
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Vamos a empezar con una aplicación mínima. Comenzaremos con una aplicación que contiene un único módulo cuyo único trabajo es mostrar texto.
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Comenzaremos creando una nueva carpeta llamada "app".
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```
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$ mkdir app
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```
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Como se mencionó anteriormente, nuestra aplicación comenzará con un único módulo o **componente** que mostrará texto en la pantalla. Podemos usar tanto JavaScript puro como TypeScript para hacer una aplicación angular 2. Usando TypeScript, es más fácil y más fácil de programar. 
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Aprendamos cómo crear un componente usando TypeScript.
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Cree un archivo llamado _`app.component.ts`_ como se muestra:
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```
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// app.component.ts
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import { Component } from '@angular/core';
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@Component({
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selector: 'my-app',
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template: '<h1>Free Code Camp Rocks!</h1>',
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styles: <a href='http://plnkr.co/edit/BdvNONEmO3Jwg0EavX22' target='_blank' rel='nofollow'>`
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h1 { color: darkgreen; font-family: Arial, Helvetica, sans-serif;}
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`]
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})
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export class AppComponent { }
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```
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Cada aplicación Angular 2 tiene al menos un componente que generalmente se llama **AppComponent** . Un componente gestiona una parte de la página utilizando la plantilla que contiene.
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Nuestro componente demuestra la estructura básica de cualquier componente que escribirá. Contiene:
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* **Importar declaraciones** para tirar de otros componentes que necesitaremos.
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* **decorador de componentes** que le permite a Angular saber qué plantilla usar y cómo se creará el componente. Básicamente, cualquier metadato relacionado con el componente.
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* **Clase de componente** que controla la apariencia y el comportamiento del componente.
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Echemos un vistazo más de cerca a cada línea en nuestro componente.
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## Importar
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```
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import { Component } from '@angular/core';
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```
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Como las aplicaciones angulares son modulares, podemos importar cualquier otro módulo o biblioteca que podamos necesitar. Aquí, estamos importando el módulo central Angular 2 para dar acceso a nuestros componentes al decorador `@Component` . Cada aplicación necesitará esta importación para empezar.
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Ya que importamos la función del `Component` anterior, ahora podemos usarla para asociar metadatos con nuestra clase de componente que le dirá a Angular cómo se debe crear nuestro componente y las acciones que proporcionará.
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## Componente decorador
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```
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@Component({
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selector: 'my-app',
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template: '<h1>Free Code Camp Rocks!</h1>'
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})
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```
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Our metadata object has selector and template fields.
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* The `selector` specifies a CSS selector that indicates which HTML element will represent this component. The element we will use will be named "`my-app`". Angular will use this to create an instance of our component where it finds this element.
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* The `template` tells angular what template it will use for this component. This can refer to other Components or just a form of HTML that tells how to display the view for our component. Our template is just displaying an `h1` element containing the text "`Free Code Camp Rocks!`".
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## Component Class
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Our final line provides an empty class named ***AppComponent***
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```js
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export class AppComponent { }
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```
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If we want to build a more complex component we can add logic and properties to the class. This component is extremely basic and simply displays some html, so its class will remain empty.
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We export our class so we can use it in other components in our application.
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Next, we need to connect our root component to Angular. To do this we create another file in our app folder called *`main.ts`* that will have the following code:
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```js
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import { bootstrap } from '@angular/platform-browser-dynamic';
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import { AppComponent } from './app.component';
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bootstrap(AppComponent);
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```
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This file imports the two items we need to start our app.
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* **`bootstrap`** - Angular's built in method that connects to the browser
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* **`AppComponent`** - Our component we created above (which is why we exported it)
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We then call `bootstrap` method with `AppComponent`
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**Finally, create index.html**
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```html
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<html>
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<head>
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<title>Free Code Camp - Angular 2 Tutorial</title>
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<meta charset="UTF-8">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<link rel="stylesheet" href="styles.css">
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<!-- 1\. Load libraries -->
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<script src="https://npmcdn.com/core-js/client/shim.min.js"></script>
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<script src="https://npmcdn.com/zone.js@0.6.12?main=browser"></script>
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<script src="https://npmcdn.com/reflect-metadata@0.1.3"></script>
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<script src="https://npmcdn.com/systemjs@0.19.27/dist/system.src.js"></script>
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<!-- 2\. Configure SystemJS -->
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<script src="systemjs.config.js"></script>
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<script>
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System.import('app').catch(function(err){ console.error(err); });
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</script>
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</head>
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<!-- Display app in my-app element -->
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<body>
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<my-app>Loading Your App...</my-app>
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</body>
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</html>
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```
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In commented section 1, we loaded several libraries that improve the compatibility of this tutorial with different browsers/versions. It also imports `system.src.js` which is used as module loader to import the app.
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In section 2, SystemJS is used to load our application and our various modules. In a production example we may want to use something else such as webpack. It was chosen here since we can use it with plunker.
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This is all that is required to get our simple application running. <a href="http://plnkr.co/edit/2i7Wjwd2JGj4NZtKvGD2" target="_blank">Here is a link to a plunker</a> that contains our working application. You can fork it into your own version and change whatever you'd like.
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<a target="_blank" href="http://plnkr.co/edit/2i7Wjwd2JGj4NZtKvGD2">VIEW APP</a>
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## Add Functionality and Another Component
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Now let's add a bit more functionality to our program. We will create a counter that let's you increment it by clicking a button.
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Our increment component will be its own module so that we can reuse it in later applications.
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Let's name our file: `app/increment-clicker.component.ts` and set it up.
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```js
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// app/increment-clicker.component.ts
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import { Component } from '@angular/core';
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@Component({
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selector: 'increment-clicker',
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template: `
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<div className="counter">
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<h1>{{curClicks}} clicks</h1>
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<button type="button" (click)="incrementClicks()">Increment</button>
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</div>
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`,
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styles: [`
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.counter {
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width: 100%;
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margin: auto;
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background: darkgreen;
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border-radius: 5px;
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color: white;
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padding: 20px;
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text-align: center;
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}
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.counter h1 {
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margin: 0;
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padding: 20px;
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font-size: 36px;
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}
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.counter button {
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background: #f1c40f;
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border: 0;
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box-shadow: 0px 5px 0px #927608;
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padding: 20px;
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width: 100%;
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outline: none;
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border-radius: 5px;
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color: darkgreen;
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font-weight: bold;
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}
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.counter button:hover {
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background: #a9890a;
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cursor: pointer;
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}
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`]
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})
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export class IncrementClicker {
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curClicks = 0;
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incrementClicks() {
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this.curClicks++;
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}
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}
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```
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Our component structure is similar to our previous one, but we've added a bit of functionality here. You will notice our class is no longer empty. We've added a variable to track the clicks as well as a function to increment them when the user clicks the button.
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You can display properties from your class in your template using double braces such as: `{{ variableName }}`
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We bind the button click event to our class function using Angulars Event Bindings.
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```html
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<button type="button" (click)="incrementClicks()">Increment</button>
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```
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Notice that we've also added some styling to our components. This way everything is self-contained in this module. You may also include a `templateUrl` and/or `styleUrls` properties instead to extract the template and style rules to an external file and link them here.
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Now we just need to update our `AppComponent` to include our new component:
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```js
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// app/app.component.ts
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import { Component } from '@angular/core';
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/* Nested Component */
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import { IncrementClicker } from 'app/increment-clicker.component';
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@Component({
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selector: 'my-app',
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directives: [IncrementClicker],
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template: `
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<h1>Free Code Camp Rocks!</h1>
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<increment-clicker></increment-clicker>
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`,
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styles: [`
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h1 { color: darkgreen; font-family: Arial, Helvetica, sans-serif;}
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`]
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})
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export class AppComponent { }
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```
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To pull in our new `IncrementClicker` component we need to import it by including the class name as well as the location of the typescript file as we did on this line:
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```js
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import { IncrementClicker } from 'app/increment-clicker.component';
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```
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We then add the `IncrementClicker` *component* as a directive to the `AppComponent` module using:
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```js
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directives: [IncrementClicker],
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```
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Finalmente, simplemente agregamos la etiqueta a la que se conecta nuestro componente en la plantilla. Por lo tanto, el selector en nuestro componente `IncrementClicker` coincidirá con la etiqueta donde queremos que aparezca.
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`js template:`
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# Free Code Camp Rocks!
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`,`
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¡Nuestro componente ahora está incluido en nuestra aplicación!
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\[Código actualizado
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[VER APLICACIÓN COMPLETA](http://run.plnkr.co/plunks/BdvNONEmO3Jwg0EavX22/)
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