Mastering Angular: Key Features and Best Practices

A TODO application in front-end development is like the "Hello World" in traditional programming. When creating TODO applications, one can study performing CRUD operations using a particular framework. However, these types of projects often only superficially address what the framework is actually capable of.

Looking at Angular, one gets the impression that this framework is constantly changing and updating. However, when it comes to Angular, there are certain concepts that remain unchanged. The material, which we are translating today, provides an overview of the basic Angular concepts that need to be understood to use the framework's capabilities correctly and efficiently.

Mastering Angular requires a lot of learning. Many developers get stuck at the early stages of learning Angular. This happens because they don't know where to go next or what key terms to search for in order to make progress. The author of this material says that when she started learning Angular 2+, she wished she had come across a guide similar to this one.

1. Angular Module Architecture

Angular applications can, in theory, be created by putting all the code on one page in a single giant function. However, this is not recommended and is also not an effective way of structuring code. Moreover, this approach defeats the very purpose of Angular.

In Angular, the concept of modules is widely used as part of the framework's architecture. A module is a piece of code that exists for one reason only. Overall, we can say that Angular applications are built from modules. Some modules are used only in one place in the application, while others are used in multiple places.

There are many ways to structure modules within an application. Additionally, learning different architectural patterns helps understand how to organize the structure of an application with an eye toward scaling it as it grows. Furthermore, the smart use of modules helps isolate code and prevents duplication across the project.

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2. One-Way Data Flow and Immutability

Many developers who used Angular 1 liked the concept of two-way data binding. This was, in fact, one of the attractive features of Angular. However, as Angular applications became more complex, it became clear that two-way binding caused performance problems.

It turned out that two-way binding is not actually needed that often. In Angular 2+, two-way binding is still available, but only when the developer explicitly expresses the intention to use it. This approach forces developers to think about the direction of data flows. Additionally, it allows more flexible work with data. Flexibility is achieved by configuring how data should flow within the application.

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3. Angular Attribute and Structural Directives

A directive is an extension of HTML through custom elements. Attribute directives or attributes allow you to modify element properties. Structural directives allow you to influence the content of pages by removing or adding elements to the DOM. For example, ngSwitch and ngIf are structural directives as they evaluate the parameters passed to them and determine whether certain parts of the DOM should be present in the document.

Attributes represent mechanisms for changing the default behavior of elements, configurable by the programmer.

Learning how to use these two types of directives will help extend the capabilities of your application and reduce redundant code. Attribute directives can also help in highlighting certain element modification templates that are used in different places of the application.

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4. Component Lifecycle Methods

Each piece of code has its own lifecycle, which defines how it is created, rendered, and then destroyed. In Angular, there is the concept of the "component lifecycle". It looks something like this:

• Creation
• Rendering
• Rendering child components
• Checking for changes in data-bound properties
• Destruction
• Removal from the DOM

The programmer has the opportunity to intervene in the component's operation at key moments in this cycle, such as responding to certain events. This allows the programmer to control how the application behaves at different stages of the component lifecycle.

For example, it may be necessary to load some data before the page is displayed on the screen. This can be done in the ngOnInit() lifecycle method. Or, at a certain point in the application, it may be necessary to disconnect from the database. This can be done in the ngOnDestroy() method.

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5. HTTP Services and Observable Objects

What we are discussing here relates more to ES7 rather than Angular-specific features. It just so happens that Angular implements working with Observable objects at the framework level. Similar mechanisms are found in React, Vue, and other JavaScript-based libraries and frameworks.

Observable objects are patterns that help work efficiently with data in event-driven systems. To effectively develop Angular applications, one needs to know how to use HTTP services and Observable objects.

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6. "Smart" and "Dumb" Components

Many developers, when building Angular applications, try to put everything necessary for the components into certain components. However, this is not necessarily the recommended practice. The concept of "smart" and "dumb" components in Angular is something that should be discussed more frequently, especially among beginner developers.

Whether a component is "smart" or "dumb" is determined by its role in the overall structure of the application. "Dumb" components often have no state and exhibit simple, predictable, and understandable behavior. It is recommended to always aim to create and use "dumb" components wherever possible.

"Smart" components, on the other hand, are more complex as they receive data as input and generate output. To effectively use Angular, familiarize yourself with the concept of "smart" and "dumb" components. This will equip you with patterns and ideas on how to organize code fragments in the application and how to establish relationships between them.

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7. Application Structure and Practical Recommendations for Its Formation

When it comes to application structure and applying practical recommendations for its creation, the Angular command-line tools can offer some assistance to the programmer. Developing an Angular application (or any other application) is similar to building a house. Specifically, it is about practical techniques that have been developed and optimized by the developer community over the years. Applying these structuring techniques leads to high-quality projects. This also applies to Angular.

When beginner programmers, trying to learn Angular, complain about the framework, the reason for these complaints is usually a lack of knowledge about application structure. Beginners easily understand the syntax, but they struggle with finding the correct approach to structuring applications. Here, it is necessary to understand the subject area for which the application is being created, to know the requirements of the application, and how reality and expectations relate on both a conceptual and practical level.

Studying possible Angular application structures and practical recommendations for using these structures will give the programmer insight into how to create their own projects.

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8. Data Binding Syntax and Templates

Data binding is probably the most noticeable feature of JavaScript frameworks. Moreover, it is one of the reasons why frameworks exist in the first place. Data binding in templates is the bridge between static HTML code and JavaScript. The data binding syntax in Angular templates serves as an intermediary, facilitating communication between HTML and JavaScript entities.

Once you learn how and when to use bindings, you'll easily be able to turn static pages into something interactive. It's recommended to pay attention to the different binding scenarios, such as property binding, event binding, data interpolation, and two-way binding.

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9. Feature Modules and Routing

Feature modules in Angular are an underrated technology. In fact, they provide developers with a fantastic way to organize and isolate sets of business requirements in applications. They help limit the responsibility of code fragments and prevent long-term code pollution.

There are five types of feature modules (Domain, Routed, Routing, Service, Widget), each responsible for implementing specific functionality. Learning how to use feature modules together with routing can help create distinct functional blocks and implement a clear and understandable responsibility division in applications.

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• Angular feature modules
• Shared feature structures in Angular
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10. Forms and Data Validation (Reactive Forms and Validators)

Forms are an inevitable part of any front-end development. And wherever forms are used, data validation is needed.

In Angular, there are various ways to construct intelligent forms driven by data. Reactive forms are especially popular. However, there are other options, such as template-driven forms and custom validators.

Learning how validators work together with CSS can speed up the development of applications and simplify error handling in forms.

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11. Content Projection

In Angular, there is a mechanism called content projection. It allows efficient data transfer from parent components to child components. While the idea of content projection may seem complex, its essence lies in the fact that to construct an element displayed on the screen, one element is placed inside another.

Developers often study content projection at a superficial level, such as getting familiar with a scheme where a child component is nested within a parent component. But to expand the understanding of this concept, one also needs to understand how data is transferred between different visual components. This is where understanding content projection comes in handy.

Understanding this concept helps in grasping the movement of data streams within an application and where mutations of this data occur.

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12. onPush Change Detection Strategy

By default, Angular uses the standard change detection strategy. With this approach, component checks occur constantly. Although there is nothing wrong with this, this change detection approach can be inefficient.

If the application is small, it doesn't significantly affect performance. However, once the application grows to a certain size, its speed, especially in older browsers, may worsen.

The onPush change detection strategy can significantly speed up the application. When using it, checks are only made when certain events occur. This is much better than constant checks.

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• Angular onPush change detection

13. Route Guards, Preloading, and Lazy Loading

If your project has mechanisms for user login, it means you need to use route guards. In many applications, it's necessary to protect certain pages from unauthorized viewing. Route guards work as an interface between the router and the requested route. They make decisions about whether access to a specific route is allowed in a given situation. There is much to learn in the realm of route protection, such as decision-making based on token expiration, using authentication roles, and ensuring secure routing.

Preloading and lazy loading data can improve user experience by reducing application load time. It's also worth mentioning that preloading and lazy loading technologies are not only related to images. These technologies are used when splitting app bundles and loading different parts of those bundles under various conditions.

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• Angular route guards
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14. Custom Pipes

Angular pipes significantly simplify data formatting. There are many built-in pipes that help solve a wide range of standard tasks. These include formatting dates, currency amounts, percentages, and working with letter case. However, there will always be tasks that do not have a standard pipe.

In such cases, custom pipes are needed. This mechanism allows developers to create their own filters and define the necessary data transformations. It is easy to use, so this concept is worth exploring.

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15. @ViewChild and @ContentChild Decorators

Components can communicate with each other thanks to the @ViewChild and @ContentChild decorators. The essence of using Angular is to make multi-component applications resemble a puzzle. However, such a puzzle is not very useful if its pieces are isolated from each other.

To connect the pieces of the puzzle, the @ViewChild and @ContentChild decorators are used. Studying how to use them will allow you to work with components that are connected to other components. This simplifies the task of sharing data between components. It also allows you to pass data and event information between components.

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16. Dynamic Components and ng-template Directive

Components are the building blocks of Angular applications. However, not all components need to be created in advance. Some need to be created during the application runtime.

Dynamic components allow the application to create what it needs while running.

Static components, in contrast to dynamic ones, are created in advance. This is done when it's not expected that anything will affect the components. They are predictable, performing data transformations in a predetermined manner.

Dynamic components, on the other hand, are created as needed. They come in handy when developing applications that work with external data sources. They are also useful when you need to respond to actions on the page.

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17. @Host, @HostBinding Decorators and exportAs Directive

The @Host, @HostBinding decorators and the exportAs directive are used in Angular to manage what they are applied to. Furthermore, they provide the ability to create concise templates for exporting entities that can be used in the application.

If the above explanation seems unclear — it’s recommended to learn more about directives and understand their purpose. The @Host, @HostBinding decorators and the exportAs directive are essential to what makes Angular what it is.

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18. State Management with NgRx

The application state determines what the user sees. If the application state is disorganized, it might indicate that the data structures used in it are poorly adapted to changes. Changes may need to be made to the data structures as the application grows and develops.

As someone begins to understand how state works in Angular, they will also come to understand the behavior of data in their applications.

Angular has its own state management system. However, there is a technology called NgRx, which allows managing application state on a higher level. For instance, data can be lost when passing it between multiple parent and child components. NgRx allows creating a centralized store to solve this problem.

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19. Dependency Injection and Zones

Dependency injection is a large-scale universal concept. If you are not very familiar with it — it’s worth studying. Angular offers many ways to elegantly inject dependencies, mainly by using constructors. It’s about importing only what is needed into the code. This helps improve application efficiency.

The concept of zones, like dependency injection, is not unique to Angular. It is a mechanism that allows an application to track the state of asynchronous tasks throughout their lifecycle. This is an important concept because asynchronous tasks can change the internal state of an application, and thus what the user sees. Zones help organize change detection processes.

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Conclusion

Building Angular applications is a vast topic. While learning by developing applications is a good way to discover new things, sometimes a person simply doesn’t know what they don’t know. Beginners especially find it hard to understand the limits of their knowledge and to see beyond them. We hope this material has helped everyone interested in Angular to outline pathways for deeper exploration of the framework.