Learn the main frontend design patterns for creating effective web interfaces.

This guide delves into front-end Design Patterns by leading you into the world of web development focused on the specific challenges of front-end design and implementation.

In this article, we will explore the major design patterns and how they can improve code organization, increase maintainability, and encourage reuse of solutions.

Get ready to discover how these tools can transform your approach to web development, simplifying the creation of intuitive and efficient user interfaces.

Index

1. Design Pattern Front-end: an Introduction
   1. Advantages of using Design Patterns
   2. Principles of Design: when to use front-end design patterns
2. The main structural pattern designs for front-end development 
   1. A classic: the MVC model - Model, View and Controller
   2. The Magical World of Web Components 
   3. The Revolutionary MVVM Model: Model-View-ViewModel
3. The 4 fundamental design patterns for a web application 
   1. Singleton Pattern: one object to command them all 
   2. Observer Pattern: let's keep ourselves informed
   3. Strategy Pattern: choose your path
   4. The Power of the Decorator Pattern
4. Modern Patterns for the UI//UX
   1. Atomic Design: build from small to large
   2. The Future of CSS: Styled Components
   3. Fluent Animations with Motion UI Pattern
   4. Principle: easily create web interfaces
   5. Adobe After Effects: advanced graphic effects
   6. LottieFiles: render animations
5. Conclusion

Design Pattern Front-end: an Introduction

Before we delve into defining the main front-end development patterns, it is necessary to define what a design pattern is. Let's see together what they are and what benefits they bring to our projects.

Design Patterns representa set of established conventions or rules for addressing common problems through repeatable computing solutions. The key word in design patterns is reuse, of code and structures.

Applying a design pattern involves creating software that follows the structure and syntax rules of the pattern(s) chosen for implementation. For example, using the Angular framework is an excellent example of applying the MVC pattern (which we will discuss later), since the framework itself was built following the rules defined by this pattern. 

Javascript beingthe key language of front-end programming and being an object-oriented language, we will analyze the main patterns intended for object-oriented programming. These, mainly describe the relationships between classes and are called behavioral patterns. I architectural patterns on the other hand, are the more high-level ones, the use of which makes it possible to create very complex systems such as, indeed, entire frameworks. 

Advantages of using Design Patterns

The main benefit of using patterns in any software is undoubtedlycode organization. When applied correctly, design patterns ensure that less code is written, as much code as possible is reused, and performance and maintain high levels of maintainability over time.

In any complex project destined to grow over time, the implementation of design patterns becomes critical. Rules shared by programmers within the team, described in documentation, to keep down the level of chaos that can arise as complexity increases and project development proceeds.

There are many common patterns shared by the software engineering community, but this does not prohibit the creation and definition of design patterns specific to each project.

Principles of Design: when to use front-end design patterns

Before even starting to write a single line of code, it is essential to establish the rules to be followed during development.

It must be remembered that applying a pattern has advantages, but also disadvantages during development. For example, it may seem excessive to apply complex patterns at the beginning of a project with only a few components, as it may represent a disproportionate effort compared to the initial complexity of the project.

However, as the number of features to be implemented increases, applying a development pattern will speed up developments. It also helps keep down technical debt and the occurrence of bugs or,in general, confusion that canemerge as the project progresses.

The main structural pattern designs for front-end development 

In the vast universe of front-end development, front-end design patterns are the foundation upon which robust and efficient Web applications are built.

In this chapter, we will explore some of the most crucial front-end design patterns , starting with the classic MVC Model (Model, View, and Controller), which revolutionized object-oriented Web programming. We will also analyze the Model-View-ViewModel (MVVM), an innovative variant of MVC. In addition, we will discover the power of the Singleton, Observer Pattern, Strategy Pattern, and Decorator Pattern in the context of front-end development.

Read on to learn how these design patterns can become a valuable resource in your development journey.

A classic: the MVC model - Model, View and Controller 

Let us start by analyzing the great classic, the pattern that revolutionized object-oriented web programming. To follow the MVC pattern, there must be a clear separation of three parts: 

1. M (model): the object that contains the data;
2. V (view): the object responsible for showing the data to the user;
3. C (controller): ensures model-view communication and contains the business logic of the program.

Using this pattern provides several advantages: multiple different views can be created using the same data model, so the view and model are for all intents and purposes distinct and reusable entities. Business logic is devolved to a single entity, the controller, and does not have to be scattered across several files or even the view, reducing the possibility of introducing anomalies during programming. 

For example, the Angular framework follows a variant of the MVC model (the MVVM, which we will discuss later), in that in a basic structure of a component we have:

1. Html + Css that make up the view.
2. The component.ts file is equivalent to the controller, which is responsible for managing the data coming from the service and applying the necessary logic to it.
3. The model is a collection of the service.ts and model.ts files, in the latter the data interfaces are defined, and the actual data is transported through the service.ts.

The magical world of Web Components 

Under the umbrella of the term "Web Components" reside suites of technologies that enable the creation of reusable custom Web elements, whose functionality is encapsulated by the rest of the code: their autonomy potentially allows them to be used in any Web application. 

It is not a new technology; in fact, we start talking about it in 2011, almost a geological era ago in computer science, but they are standardized in the following years and there are different implementation techniques:

1. Custom Element: permette di riservare una porzione di html definita da un <tag> in cui verrà renderizzato il componente. 
2. Shadow DOM: replicates the DOM (Document Object Model) of the web page but only within a component, allowing two completely separate DOMs to actually be managed within the same web page. 
3. HTML Template: behaves in effect like a framework, that is, it renders portions of the page within specific tags but without affecting or being affected by the page it is on.

Angular Elements is a package of the Angular framework that allows you to create and expose web components, which can be used in any web page that runs some JavaScript without needing to import the entire framework to make them work. 

The Revolutionary MVVM Model: Model-View-ViewModel 

A variant of the classic MVC model is the Model-View-ViewModel.  

In this structural pattern it is intended to give a more important role to the view, including in it validations, data-binding, and other logic that would usually be devolved to the controller. 

This pattern consists of only two entities:

1. View: not only shows data to the user, but logic can be inserted into it, which at the discretion of development decisions, can include logical loops, validations, operations, and especially data-binding.
2. ViewModel: is the equivalent of the controller and incorporates the functions of the Model, basically getting and persisting data, but can contain logic like a controller. 

As mentioned earlier, a very successful example of this pattern is undoubtedly Google's framework, Angular. Framework, which you can learn more about in this article, where Vincenzo introduces us to the main differences from the React library.

The 4 fundamental design patterns for a web application 

Singleton Pattern: one object to command them all 

The Singleton is one of the fundamental patterns for the development of any application. To apply this pattern, one must ensure that a single instance of a class exists before creating a new one.

Of course, there are cases when it is essential to create a new instance of an object. Let us imagine the case of creating new users in a database: when a new user is expected to subscribe to a service, each user must have its own "instance" separate from the others, so as not to mix information from different users.

Instead, in case you are creating a service that needs to provide common and shared information with other classes, this service must be generated as a singleton.

To do this, simply verify that there is not already an instance of the object started in the application with each new request: if it exists, you must return the instance already running, and if it does not exist, you must create it.

An example of a Singleton that is widely used in Web applications is the logger. The logger is a useful tool for programmers to return messages about what is happening in the code during execution.

Common logic is contained in the logger that cannot be replicated or reinstantiated every time a log request is made by the application, so the log service must be generated as a unique entity that can be invoked from anywhere in the application.

This is a great example of singletons in action, especially if you are using some error-tracking tool: you don't have to worry about losing logs generated in different instances, since there is only one.

Observer Pattern: let's keep ourselves informed 

The Observer pattern is the classic example of a pattern that, the more you study it, the less you understand it. It is a programming principle used in any event-driven management system. 

In this pattern, an object, called an observer,registers on a subject, referred to as the subject. When these objects change their state, the observer issues an event.

To make a comparison with the MVC pattern, the model is the subject, while the view is the observer. When the model changes, the view detects it and issues an event, which in this case represents a change in the displayed data. 

Observer enables a one-to-many relationship between the subject and its observers. Some examples of Observer include sending notifications to users, such as emails or newsletters, or app notifications.

Strategy Pattern: choose your path 

The Strategy pattern isuseful when you have several implementations of a feature. In this way, you delegate the containment of the different logics to a class, through which the client can choose which implementation to use, while remaining independent of the logic itself.

It is basically aninterface that simplifies the client's logic. For this reason, it is called a "strategy," because depending on the conditions specified in the client, the best strategy is selected.

By generalizing and centralizing the logic that the client can use, there is no need to repeat it each time, and the derived class remains disconnected from the interface.

The Power of the Decorator Pattern 

There is often a need to add metadata, methods, properties, or parameters to a class without propagating them by inheritance to its related subclasses.

This is where the Decorator pattern, with its immense power, comes to the rescue. Decorators are now supported by most object-oriented languages and take different forms, but the concept is unchanged: a little magic word usually preceded by "@," which describes to the compiler what properties should be added to a specific class or object, without interfering with anything else. 

In Angular, for example, you decorate a class with "@Component," to indicate that that class will be of type "component" so it will contain a constructor, optional methods such as "ngOnInit()" to perform actions upon creation of the class, or "template" to indicate that the component will need to render something within an HTML tag.

Nothing prohibits the creation of custom decorators, with custom properties and methods, which can be inserted into a class to give it specific behaviors uniquely. 

Modern Patterns for the UI//UX 

In the ever-evolving world of front-end design, a focus onuser experience (UI/UX) and the adoption of modern patterns is a key pillar for creating engaging and functional interfaces. In this chapter, we will explore some of the most innovative methodologies and approaches for designing and developing cutting-edge user interfaces.

Patterns covered in this second part of the article include,Atomic Design, which guides us in building interfaces from atomic components, Styled Components, a library that integrates CSS directly into JavaScript code, and the Motion UI Pattern, which emphasizes animation and motion to enhance the user experience. But let's take a closer look in detail.

Atomic Design: build from small to large 

Atomic Design is not a true pattern defined in the great manual "Design Patterns" by the Gang of Four (Gamma, Helm, Johnson, Vlissides), but is a modern version of the structural pattern "Composite." Its usefulness lies in constructing interfaces or elements composed of small components, as if they were atoms making up a complex system. 

In this scenario, a custom button and icon are not repeated continuously but become components that are reused in many parts of the application. 

These small components compose precisely such a complex and dynamic system as a modern Web page, are as agnostic as possible to what they have around them, and once their logics are defined these can be invoked anywhere in the application. 

In atomic design, 5 stages are succinctly defined: 

1. atom: the single button, input, or element on the page. 
2. Molecule: by itself the button serves no purpose, if placed in a form, for example, it acquires a purpose and forms a molecule. 
3. Organism: molecules joined together form a complex organism, an analogy that in computer science can have as an example a web page header, where the login button, a search bar, the site logo, and so on can coexist. 
4. Template: at this stage the organisms are put together on the page to create something more complex, namely the layout. 
5. Page: the collection of various templates finally composes what the user sees as a whole, that is, a page. Each page can have different templates, depending on how their layout is defined.

The advantages of this method of working are obvious: code reuse, focus on usability, and creation of small parts with low complexity.

The Future of CSS: Styled Components

Styled-components is a React.js plugin that allows you to do a curious thing: write CSS directly in Javascript, without the use of an actual CSS file. 

Why this complication, you will say? 

There are some advantages to using this method, let's see them together: 

1. Freedom to create custom components that include CSS within them: thanks to this library, you can create React components that already contain their styling. 
2. You no longer have to worry about collisions between class names and attributes: This is because the library takes care at runtime to replace class names with unique names, without the developer having to worry about naming the classes. 
3. Supporto nativo dei temi: la libreria permette di creare dei tag <ThemeProvider> che semplificano la creazione di diversi temi: creiamo un tema, wrappiamo qualunque componente con quel tema, o anche l’intera applicazione, e la libreria si occuperà di trasferire il CSS ai componenti wrappati. 
4. Allows you to write conditions within CSS in a convenient and controlled way: one of the most frustrating things about writing CSS styles is conditions: CSS styles are static, they cannot adjust to dynamic conditions. Styled-components allow if-else conditions to be created within the CSS itself, giving dynamicity to graphics as needed. 

Fluent Animations with Motion UI Pattern

The Motion UI Pattern is a new design trend concerning moving elements in web and mobile applications. Again with an eye toward dynamicity, motion UI focuses on creating elements that move in accordance with their function. 

For example, clicking a button that removes an element from the page, such as removing a product from a virtual shopping cart, should not cause the element to disappear immediately, but, according to the Motion UI Pattern, it should cause a gradual disappearance, perhaps with a red background. In this way, the user can have conception of what is happening even just from the interaction they have had with the element. 

A loading bar, fading by moving from one page to another, a play button that flashes when pressed to listen to a song, are all examples of motion design devoted to clarity and understanding of interaction. 

To apply this design there are a variety of techniques to be applied, especially regarding CSS styles, which make user interfaces animated. 

Animations were introduced with the advent of CSS3. The CSS property that is the queen of these animations is undoubtedly transition: this allows the value of a property to change gradually, with a set duration. 

So here we can vary the size of an element with the width property during the hover event, and a specific transition duration. 

Of course, there are plenty of tools that make creating animations much easier than manually writing CSS code, of which we see a few examples below. 

Principle: easily create web interfaces

Principle is software for the Mac that makes it easy to create mobile and Web interfaces, adding animations and interactions via predefined prototypes. It consists of a basic whiteboard, called a canvas, where you drag and drop elements that can be styled without writing a line of code. 

Another great advantage of this software is the ease with which data can be imported from other design software, such as Sketch and Figma.

Adobe After Effects: advanced graphic effects

Adobe After Effects is Adobe's very popular video editing software, also available for Windows, Adobe Premiere's counterpart for video editing, has always been the most widely used animation tool. As a more complex tool than Principle, which is more geared toward creating advanced graphic effects, it is also emerging as an essential tool for animating web and mobile interfaces. 

One of the main reasons for the popularity of this software among motion designers isthe Bodymovin plug-in, which allows the export of web-usable code, making it easier for developers to implement animations.

 

LottieFiles: render animations

Using animations generated by graphics tools in applications or Web sites has always been very complex. Problems related to GIFs, huge amounts of code, and excessive use of memory space made the user experience slow and implementation for the developer painful. 

In this scenario, the Lottie library is available to easily render animations exported from After Effects via the Bodymovin plugin, in web and mobile applications. 

LottieFiels works by means of small JSON files , which can be imported into a specific proprietary player within a web page. 

It is noteworthy that the Lottie community is constantly growing and new animations are constantly being made available for free, either in the form of JSON files or as GIFs or short videos. 

Conclusion

In conclusion, front-end design patterns are a valuable tool for Web developers, enabling them to successfully address the challenges faced in designing and implementing modern user interfaces. Through the analysis of major design patterns, we discovered how the application of structured rules and consistent syntax can help improve code organization and maintainability over time.

Always remember to choose the design pattern best suited for your project, taking into account the specific needs and challenges you will face.

Continue to explore the different possibilities offered by front-end design patterns and stay up-to-date on the latest trends in the world of web development on our blog! Start learning more about future JS frameworks.