Apprenez Angular dans ce cours gratuit en 33 parties par Dan Wahlin, expert angulaire

Selon l'enquête des développeurs Stack Overflow 2018 , Angular est l'un des frameworks / bibliothèques les plus populaires parmi les développeurs professionnels. Donc, apprendre cela augmente considérablement vos chances d'obtenir un emploi de développeur Web.

C'est pourquoi nous nous sommes associés à l'un des experts les plus renommés du framework et avons créé un cours Angular gratuit chez Scrimba.

L'instructeur Dan Wahlin est un expert en développement Google qui a fourni des services de formation, d'architecture et de développement à certaines des plus grandes entreprises du secteur et a créé certains des cours de formation les plus populaires sur Udemy et Pluralsight. Il est également un conférencier régulier lors de conférences de développeurs à travers le monde.

Dans ce cours, Dan vous guide dans la création de votre toute première application Angular à l'aide de TypeScript. En complétant le cours, vous ajouterez des compétences précieuses à votre ceinture à outils.

Voyons maintenant comment le cours est structuré!

Partie # 1: Aperçu du cours

Dans la vidéo d'introduction, Dan donne un aperçu du cours, des aspects clés d'Angular et de la façon dont le cours est organisé. Il vous parle également un peu de son parcours, afin que vous le connaissiez avant de vous lancer dans le code de votre nouvelle application.

Partie # 2: Présentation de l'application

Dans cette partie, Dan nous donne un aperçu de l'application que nous allons créer. Il est conçu pour nous permettre de nous concentrer sur les éléments de base clés d'Angular. En créant une application pour afficher les données des clients et leurs commandes, nous nous concentrerons sur les aspects clés d'Angular, tels que les composants, les modules, les services et le routage. En outre, pendant le cours, nous découvrirons les fonctionnalités intéressantes de chaque application, comme le tri et le filtrage.

Partie # 3: CLI angulaire

Dans cette partie, nous apprenons les bases de l'utilisation de l'outil Angular CLI (interface de ligne de commande) et parcourons les commandes de base:

ng --version ng --help ng new my-app-name ng generate [component | directive | pipe | service | class | interface | enum | guard] ng build ng serve ng lint ng tests 

Par exemple, ng --new my-app-namecréera une nouvelle application angulaire vierge pour nous et nous pouvons l'utiliser ng -generatepour créer des parties de notre application.

ng buildconstruira tout pour nous, et ng serve -olancera même un serveur de développement et ouvrira une fenêtre de navigateur dans laquelle nous pourrons voir notre application.

Partie 4: Présentation des fichiers de projet

Dans cette vidéo du cours, Dan donne un aperçu de base de la commande CLI pour générer une application angulaire vierge et donne un aperçu rapide des fichiers de configuration comme tslint, tsconfiget protractordans notre dossier d'application.

Partie 5: Vue d'ensemble

Ici, nous apprenons une abstraction utile selon laquelle les composants sont similaires aux blocs Lego - nous construisons des composants, puis les utilisons pour les coller ensemble pour créer une application. Nous obtenons également un rappel rapide sur la famille de langages JavaScript et apprenons où se situe TypeScripts.

Dan nous donne un bon modèle mental à utiliser pour réfléchir à notre code tout en travaillant avec Angular afin que nous puissions imaginer où tout cela s'intègre.

Partie # 6: Composants et modules - Vue d'ensemble

Non résumé, le diagramme du code angulaire pourrait ressembler à ceci.

Les composants sont composés de code et de modèle HTML et peuvent avoir un sélecteur, nous pouvons donc l'appeler dans notre HTML.

Chaque composant se compose de:

Dan explique ensuite ce qu'est chacune des pièces et comment elles s'intègrent dans la manière angulaire de développer des composants. L'un des avantages d'Angular est qu'il est très prévisible. Une fois que vous avez appris à créer votre premier composant, vous êtes sur la bonne voie pour créer des composants supplémentaires.

Partie 7: Composants et modules - Composant d'application

Dans cette partie du cours, nous examinons un HelloWorldcomposant.

Dan décompose chaque aspect du composant pour nous et explique comment il est utilisé et comment notre composant est traité par Angular, comment il est ajouté app.moduleet finalement comment il est rendu sur nos écrans.

Nous apprenons que selector: 'app-root'c'est ce qui nous permet d'appeler plus tard le composant à partir de notre HTML en utilisant

Nous avons également un aperçu de la liaison de données sur laquelle nous en apprendrons plus dans les chapitres suivants.

Partie # 8: Composants et modules - Module d'application

Dans ce screencast, nous passons plus de temps à apprendre le fonctionnement interne app.moduledont nous avons parlé dans le casting précédent et apprenons sur NgModuleet BrowserModule.

Partie # 9: Composants et modules - Ajout d'un composant clients

Dans ce casting, Dan nous donne quelques conseils sur la création de composants à l'aide de la CLI, puis montre comment créer des composants manuellement. Nous apprenons à structurer un composant en élargissant davantage nos connaissances à partir de la partie 6.

Nous apportons maintenant des données pour imiter notre API et apprenons comment les modules nous aident à garder notre code organisé et plus facile à réutiliser.

Partie # 10: Composants et modules - Ajout d'un composant de liste de clients

In this part, we create a customers-list.component which is an HTML table to display our list of customers. We quickly register in customers.module and use the selector to display our empty table.

Next step would be to populate the table with some data.

Part #11: Components & Modules — Adding a Filter Textbox Component

Before we add some data to our table, Dan shows us how to add a filter-textbox.component to our table and we reinforce the Angular way of creating a component, registering it in a module and using it in our HTML with selectors.

Part #12: Components & Modules — Adding a Shared Module and Interfaces

In this section, Dan talks about using shared.module — a module where we put components or other features that we want to share throughout our app, not just in customers.

We also have a quick refresher on TypeScript interfaces and how they can be used in Angular applications to provide better code help and enhance productivity.

export interface ICustomer { id: number; name: string; city: string; orderTotal?: number; customerSince: any; } 

Part #13: Data Binding — Data Binding Overview

In this chapter we learn about data binding, learn a few techniques and see how to add data binding to our application.

We usually bind data in our templates. Data binding comes into play when a component gets our data and hooks it into a template. We can get data into a template using Property Binding, and handle user events and get data out of a template using Event Binding. Angular provides a robust and clean way to add data binding in templates that’s quick and easy to remember.

Dan provides us with a handy slide to remember syntax required…

…and some on Angular directives, for example, ngFor, used to loop through items in a collection and get some properties from the items, and ngIf to add and remove an HTML element from the DOM.

Part #14: Data Binding — Getting Started with Data Binding

In this cast we play around with Property Binding and Event Binding to better understand how they work in Angular, using the knowledge from the previous chapter.

Dan shows how we can use the [hidden] property to display an h1 element dynamically:

{{ title }}

And to bind DOM events such as click:

Show/Hide 

Part #15: Data Binding — Directives and Interpolation

Here we have a look at Interpolation. The rationale is that we need to get data from each customer to generate a table row in a table from Part #10.

This is the part when things start coming together: we use directive ngFor to loop through each customer in filteredCustomers and interpolate data from a customer into a table row. We learn a few tricks about rendering data conditionally using ngIf.

In the end we get a pretty looking table!

Part #16: Data Binding — Event Binding

Event Binding is crucial when we need to handle an event, like a mouse move or a click. In this screencast, Dan guides us through adding functionality to sort the data in our table. We will start on it in this chapter and finish it when we get to the Services part of our course.

We create a placeholder event handler in our customer-list.component:

sort(prop: string) { // A sorter service will handle the sorting } 

Add binding in customers-list.component.html:

NameCityOrder Total

Part #17: Data Binding — Input Properties

We have some data in a people array in our customers.component and we need to pass it into our filteredCustomers array in customers-list.component, effectively passing data from a parent component to a child.

For that we will use Angular’s Input property which relies on a decorator named Input():

@Input() get customers(): ICustomer[] { return this._customers } set customers(value: ICustomer[]) { if (value) { this.filteredCustomers = this._customers = value; this.calculateOrders(); } } 

And bind to it in our parent component template to pass data from parent to child (app-customers-list in this case):

Part #18: Data Binding — Working with Pipes

Wow! We’ve done quite well so far!

There are a few things which might look a bit odd — “john” is lowercase and we have no “$” symbol to display currency in which we have our orders.

This is really the way we have our data, so we could just go and update it directly, or we can use a built-in Angular feature called Pipes to update it for us!

Some of the simplest pipes look like this:

{ uppercase } // renders JOHN { cust.name } // renders John 

But sometimes you might want to have your own custom pipe and Dan shows us how to build a custom capitalize pipe (note that Angular includes one called titlecase — but we’re learning here!) and how to wire it up to use in our application.

Part #19: Data Binding — Adding Filtering

In this cast, Dan walks us through adding functionality to our filter-textbox.component from Part #11

We learn more about Angular Output and EventEmitter properties, create our filter event handler and bind it to our filter textbox:

And there we go, we can now filter on our customers’ names!

Part #20: Services and Http — Services Overview

In this chapter, we look at Angular Services. One of Angular’s strong points is that it’s a complete framework that provides built-in support for managing state and objects through services. We saw services in the diagram earlier. Since we don’t want components to know how to do too much, we’ll rely on services to communicate with the server, perform client-side validation or calculations, etc.

Components should focus on presenting data and handling user events. When additional functionality needs to be performed they should delegate to services to provide for a more maintainable application and better code reuse.

That’s exactly what Service does — some reusable functionality for the app which should not be of any component’s concern.

Luckily, Dan get us covered with a handy slide to keep in mind.

Part #21: Services and Http — Creating and Providing a Service

From a chapter earlier we have seen an import of Injectible which is a decorator that allows for something called Dependency Injection or DI for short (another powerful feature built-into Angular).

We’ll use DI to access an HttpClient service which we will use to communicate with a RESTful service. We will be adding HttpClient to a constructor of our data.service and @Injectible() decorator will make DI possible.

Part #22: Services and Http — Calling the Server with HttpClient

In this cast, Dan introduces Observables from RxJS — reactive extensions for JavaScript, which is not a part of Angular but is included in all Angular projects by default.

We will be using Observables to deal with asynchronous code. In a nutshell, it allows us to start an operation and then subscribe to data that is returned. Once the data comes back from the server, the subscription ends and we can unsubscribe.

Dan discusses the necessary code to call the server and then subscribe to the response using RxJS piping and operators.

Here’s an example of how we can get Orders:

Part #23: Services and Http — Injecting a Service into a Component

Now that we have a way to get the data, we need to inject the service into one of our components. We can now change this.people in customers.component from being hardcoded to call a service and get data that way.

We need to bring our data.service to app.module and then in customers.component we can:

import { DataService } from '../core/data.service'; 

Now we can inject our DataService straight into our component’s constructor:

constructor(private dataService: DataService) {} 

Part #24: Services and Http — Subscribing to an Observable

Now we can use our injected dataService, call getCustomers() and subscribe to our Observable to get the data.

Which is pretty straightforward:

ngOnInit() { this.title = 'Customers'; this.dataService.getCustomers() .subscribe((customers: ICustomer[]) => this.people = customers); 

Now we have one last service to look at — SorterService

Part #25: Services and Http — Using a SorterService

Currently, if we click on our column headers nothing would happen.

Dan handily provided a prewritten service for us, which we can use, so in this chapter, we will practice bringing in service into our components, in this case, customers-list.component.

As with other services we need to import it:

import { SorterService } from '../../core/sorter.service'; 

Then we inject SorterService into our constructor:

constructor(private sorterService: SorterService) {} 

Dependency injection makes it extremely easy to access reusable code such as the sorter or data services.

Lastly, we use it in our sort() function:

sort(prop: string) { this.sorterService.sort(this.filteredCustomers, prop); } 

Part #26: Routing — Routing Overview

This chapter will introduce Routing, which is an essential part of modern applications. As you’re building an Angular app, you want to show different components as the user interacts with it. In our case, when a user clicks on a Customer, we might want to show them Orders. Routing is one way to very neatly achieve this.

Routes are used to hook a specific URL to a component and in the next few chapters, we will be focusing on the top part of our Angular diagram.

A super great part of routing is that if a user bookmarks a specific URL, it will bring them back to a specific component and there is no need for complex show/hide logic.

Part #27: Routing — Creating a Routing Module with Routes

We begin with a familiar module-container routine and create a app-routing.module.

A main focus of the app-routing.module is to define the routes in an array:

const routes: Routes = [ { path: '', pathMatch: 'full', redirectTo: '/customers'}, { path: '**', redirectTo: '/customers' } ]; 

Three key properties of routes are:

  • path — where your user goes, so path: '' would be the root of your app. path: '**' is a wild card match. It is usually placed last and it’s there to cover cases for any route that is not specified in routes
  • pathMatch — how exactly should the route match for a specific component to be displayed
  • redirectTo — when a path is matched, this is where we send the user. In our case, we send them to /customers.

Part #28: Routing — Using Router Outlet

In order to use Routing in Angular in our app.component template we replace with . Ultimately, this is just a way to say: ‘Hey, this is where a component will go when we hit our route’.

When we hit a route, then a component associated with that route will magically appear in the place of .

Part #29: Routing — Adding a Customers Routing Module and Routes

In this chapter, Dan brings all the things together and we connect a /customer route to customers.component.

First, we create acustomers-routing.module and point our route from part #28 to customers.component like so:

const routes: Routes = [ { path: 'customers', component: CustomersComponent } ]; 

And now when we type “customers” in the Scrimba browser address bar we get our customers.component.

Part #30: Routing — Adding an Orders Component with Routes

In this clip, we’re going to quickly review how we’ve done routing to display customers, and now it’s time for routing to display their orders.

There’s a little catch though. When we click on a customer we need to display order data related to that customer. So we need to pass some dynamic data into our routing.

We can achieve this by passing a route parameter in our orders-routing.module like so:

const routes: Routes = [ { path: 'orders/:id', component: OrdersComponent} ]; 

Note the /:id syntax. In routing the : symbol indicates that the value after it will be dynamically replaced and id is just a variable, so it can be anything like :country or :book.

Part #31: Routing — Accessing Route Parameters

In the previous screencast we saw how to create orders/:id route and now orders.component needs to somehow grab that id and display customer related orders. To do that we need to access the id route parameter.

One way of doing it would be:

let id = this.route.paramMap.get('id'); 

The benefit of this way is that we can subscribe to paramMap and get notified when any of the data in id changes. But we only need it once.

We can use snapshot for that:

let id = this.route.snapshot.paramMap.get('id') 

snapshot just takes a kind of an instant picture of your URL and gives it to you, which perfect as that’s what we need in this situation.

But now we have a problem. Our id is a string, but to get an order from our DataService it needs to be a number. We can convert it with parseInt(), but Dan teaches us a neat + trick:

let id = +this.route.snapshot.paramMap.get('id') 

Now we can call DataService to get the order and render it to orders.component.

Part #32: Routing — Linking to Routes with the routerLink Directive

The last thing we want to do is to add a link on a customer’s name, so we can click it to see their orders.

In part #28 we’ve added and now we just need to tell our app that we want to display orders.component when we navigate to /orders/:id.

We can do it by adding a link to our customer’s name in customers-list.component.html in a row where we’re mapping all the data to be displayed. We already have our customer object there, so we can just pass id to our route.

 { capitalize }  

Now we can see orders!

Original text


But hey, how do we get back? We could click ‘Back’ button on the browser, but it’s much nicer to have an app link for that, now that we know routing. Let’s add it to customers-list.component.html at the very bottom.

View All Customers 

Part #33: Course Summary

Very well done, we have our app now!

We can wrap up and have a quick recap of things done. Don’t forget to watch the actual screencast of the course, as Dan is a great teacher so you will have lots of fun following the process alongside him!

Thank you, Dan!

If you’re interested in keeping up on front-end and back-end technologies make sure to follow Dan on Twitter!

Happy coding!

Thanks for reading! My name is Per Borgen, I'm the co-founder of Scrimba – the easiest way to learn to code. You should check out our responsive web design bootcamp if want to learn to build modern website on a professional level.