Roadmap for Angular: A Beginner Guide
Hello, readership and welcome to the universe of coding! If you are here, it means that you are on the beginning of your programming path as an Angular developer. Actually, it is very good that for the first tries of writing a code you have chosen such a framework as Angular. I hope that this article will be a helpful magical stick for you that will inspire you and explain some of the simplest basic things about Angular. I will mainly tell here about how the application may look inside and answer several questions that will be your roadmap in your Angular app development. So, let’s start.
What is the application like in Angular?
Well, to be more specific, I would rather say that your application is a component tree.
When a developer receives a picture of a prototype of a future application, he begins by breaking it down into components. Any Angular application has one root component, which can include other components (“children”), and those, in turn, can include their children (“grandchildren”). Let’s say you decide to rewrite Twitter UI in Angular. Start by breaking it down into components.
Turn on your imagination. Imagine that the root component is shown in a red box, and it includes several children. In the middle at the top, you can place a New Tweet component (in a blue frame), under which there will be instances of the Tweet component (shown in yellow frames), which also have “children” shown in black frames (reply, retweet, like, and direct messaging).
A parent component can pass data to a child component by using a data binding to the child properties. The child component is pretending to be an orphan like I don’t know either mom or dad. Such a child does not care where the data came from. But this orphan still has a glimmer of hope that a parent will be found, so the child can generate events and send messages with data upstairs. Who? Anyone who wants to receive and process them. This architecture makes the components self-contained and can be used in different applications.
How to separate UI and application logic during Angular development?
Well, I must say that the big advantage of Angular is a very clean separation between UI and application logic, which makes it very attractive for the developer’s community.
A component is a TypeScript class annotated with the @Component decorator, where you specify the component metadata: HTML and CSS. They can be implemented either in separate files, or directly in the decorator (inline), as in this example:
@Component ({
selector: ‘home’,
template: `<div class =” home “> Home Component
<input type = “text” /> </div> `,
styles: [`.home {background: red; padding: 15px 0 0 30px;
height: 80px; width: 70%;
font-size: 30px; float: left;} `]})
export class HomeComponent {
// Implement business logic here
}
When the template (HTML) or styles consist of many lines, they can be kept in separate files:
@Component ({
selector: ‘home’,
templateUrl: ‘./home.component.html’,
styleUrls: [‘./home.component.css’]
export class HomeComponent {
}
How to navigate the client-side using the router?
Angular is good for creating single-page apps (SPA). The browser does not reload the entire page, but only its fragments, as the user interacts with the application (clicks on buttons, links, etc.). Angular has a Router to navigate within the app. Inside the component template, using the <router-outlet> tag, you can select one or more areas to display different parts of the page. For example, in the Twitter app, you can highlight the middle section of the page under the <router-outlet>, and if the user clicks on the Notifications menu, another component will be shown in that area.
How to modularize the application in Angular?
When you create an app, an important step is to divide it into several modules. I advise you to maintain one module that will be the root one and set the minimal functionality to it. Then, after this step is done, you can easily implement separate modules, for example, Billing, Shipping, etc.
In addition to this, there is one thing that may help you to minimize the size of the application. What is this? Well, this is the loading of these modules inside. For example, the “Pay” button only loads when the Billing module is loading. So with the help of modules, you can easily make these things work automatically, and they will load the background after the main page has already been opened and the user has begun interacting with the app.
How to deal with dependency injection?
Components are classes that have a UI, and services are classes that contain application logic. You write such a class, for example, Product Service, and Angular creates an instance of it and injects it into the Product Component. To do this, you just need to specify the service as an argument of the component constructor and you do not need to create an instance of the class using the new operator:
@Component (…)
class ProductComponent {
constructor (public productService: ProductService) {}
onClick () {
this.productService.getProducts ();
}
}
In this example, we are using the service API in the click event handler.
What is TypeScript and how to use it properly?
New versions of Angular are written with the help of TypeScript and I surely recommend you to deal exactly with this language. The main advantage of it is that in an autocomplete way it highlights syntax errors quite quickly and you don’t have to wait until the program is launched and compiled. With this amazing feature, the developer productivity and speed of making an app is increasing every day.
Typescript is easy to learn for anyone who knows Java, C #, PHP, or Python. This language supports classes, interfaces, inheritance, generics, and more. You write in TypeScript and compile the code to JavaScript that all browsers understand. Take a look at this screenshot and compare the TypeScript code on the left with the generated JavaScript (ES5) equivalent on the right. I don’t know about you, but I like the TypeScript version better.
All browsers support the JavaScript syntax of ECMAScript 5 and most modern browsers already support ES6, which has added many elements including classes. ES7 and ES8 have added a bit, although an important improvement is the introduction of the async and await keywords to break out of callback hell. If you write in TypeScript, you can use the latest innovations today, and the compiler itself converts the code into the version of JavaScript that is supported by all browsers.
How to slap the forms in Angular?
It’s hard to imagine a web application that doesn’t need forms. Well, at least you need to log in?
Behind each form is an object with a data model that stores all the values entered by the user. Angular offers two APIs for forms: template-driven and reactive. One that is template-driven allows you to code forms without the hassle of creating a model in TypeScript. Just sprinkle HTML forms with a few directives, and Angular will create the model itself.
For more advanced work with forms, use the reactive Forms API. Here you will code the model object in TypeScript yourself, but you will have more control over the behavior of the form.
Both the template-driven and reactive APIs have built-in validators and allow you to use custom ones so that the user doesn’t have to enter into something. It is possible to organize validation on the server using so-called asynchronous validators.
Does Angular support the reactive programming?
Recently, reactive (RX) libraries have become popular, which are built on working with observable data streams that are generated asynchronously by some source, for example, mouse events, sensors, sockets, etc. Such libraries include a large set of operators that are easy to assemble into a chain for data manipulation along the road from the data source to the subscriber. Angular comes with the RXJS library and you can either subscribe to ready-made observable streams provided by various APIs or create such streams yourself.
Let’s say the user enters the name of stock from the financial exchange into the searchInput field. The following code subscribes to the valueChanges stream (all Angular form elements have it) and wants to make a request to the server to receive the changing prices for these shares. To minimize the number of requests to the server, we use the debounceTime statement so that the getStockQuoteFromServer () function is called only if the user does not enter anything for 500 milliseconds.
this.searchInput.valueChanges
.debounceTime (500)
.subscribe (stock => this.getStockQuoteFromServer (stock));
}
The code is compact, but be prepared to take the time to learn the RxJS library. In this example, I put one debounceTime statement between the data source and the subscriber, but I could chain multiple statements like map and filter. You can add one line with the switchMap operator, which will automatically unsubscribe from requests that have not yet returned (slow internet), and the user is already entering a new value. Try canceling unnecessary requests for simple Ajax calls – you won’t get by with one line.
How to create a modern UI using Angular?
Many web applications use the popular Bootstrap library to style and layout pages. You can use this library in Angular applications. Bootstrap supports responsive web design so that the layout of UI components automatically adapts to the width of the user’s device screen.
There are other libraries made especially for Angular. Angular Material is a library of 30 modern components made according to the Google Material Design specification. If you need more components, use one of the third-party libraries. So, for example, PrimeNG includes 75 UI components made specifically for Angular.
How to make an Angular app adapted to different mobile devices?
There are different approaches to make your application look good on various mobile devices, for example:
- Use the same code for desktops, tablets, and smartphones, but implement responsive web design techniques to change the content and layout of the screen based on its size.
- Use one of the libraries (for example Native Script) that offer a set of tags for using Angular components in templates with auto-replacement for native iOS or Android
What is server-side rendering and what does it make?
Server-side rendering (SSR) further improves rendering speed in browsers. SSR still on the server prepares an HTML page from your Angular application. This is especially useful if your users use mobile phones or if it is important for you that the application is better found by search engines. Angular Universal is a technology that generates static web pages on the server.
Conclusion
To summarize everything written above, I will say that Angular is a great framework to start with. Learning and practicing just the basics, you can already start making your first money on it. Do not be afraid to accept challenges and be patient. Thank you, novice, for reading this article and I really hope it was useful for you. Good luck on your programming path – not easy, but still full of excitement.
