Design patterns are advanced object-oriented solutions to common software problems. Pattern refers to reusable design and interactions relating to objects. When you talk about complicated design decisions, all templates are named and forms part of the vocabulary. JavaScript design patterns are called problem-solving patterns. However, this does not mean that these templates can be a replacement for developers. Design models help with the combination of experiences from different developers to structure the code in a streamlined way that matches the problems we want to solve and provide a common vocabulary that explains the solution to our problems, rather than the syntax and code semantics.
This article will examine some of the best and commonest design patterns in JavaScript, which fall into three categories: best modeling practices, structured design models, and behavioral design models. They are as follows; structural design patterns, behavioral design patterns, and creative design patterns.
Advantages of Design Models
Solutions are proven: Since several developers widely use design layouts, you can be sure they will work. Not only that, you can be sure that they have been tested several times and that the optimization has probably been implemented.
They are easy to reuse: Design Patterns features a reusable solution that can be modified to address a few specific problems as they are not related to a specific problem.
Expressive: the design patterns explain the big solution cleverly.
They make communication easier: once developers are good with design patterns, they can communicate more easily with each other about possible solutions to a specific problem.
Avoid the need to refactor your code: If your application was written with design patterns in mind, you generally don’t need to refactor your code later because the correct design pattern is already optimally applied to the problem.
They reduce the codebase size: since design patterns are generally elegant and ideal solutions, they generally require less code than other solutions.
Module Design Pattern in JavaScript
JavaScript modules are the most common design patterns used to keep certain code pieces separate from other components. It provides a coupling for supporting a well-structured code. If you are not new to object-oriented languages, you will understand that modules are JavaScript classes. One of the benefits of classes is encapsulation — blocking access to states and behaviors by other classes. The module standard enables both public and private access levels (plus protection and less common privileges).
The modules must be IIFE — Immediately-Invoked-Function-Expressions to enable private scopes, a closure protecting both variables and methods (but returns an object instead of a function). A change in the module pattern is known as the Revealing Module Pattern. The aim is to maintain encapsulation and expose certain variables and methods fed back into a literary object.
Observer Design Pattern in JavaScript
When one part of the application changes, there is always a need for the other parts to be updated. In AngularJS, when the $scope object is updated, an event can be raised to make another component aware. This is exactly what the observer model does: when an object is changed, it transmits to dependent objects that change has taken place. Another important example is the MVC (Model View Controller) architecture. The preview is updated when there is a change in the model. The decoupling model view is an advantage to reduce dependencies.
In the observer design pattern, it is essential to differentiate between the independent object and the subject. It is imperative to note that even though the observer model has a lot of advantages, one of the drawbacks is a major decrease in performance as there is an increase in the number of observers. Watchers are one of the most famous observers. In AngularJS, variables, functions, and objects can be watched. The $$digest cycle quickly notifies all watchers with new values when a scope object is changed.
Singleton Pattern
This is important where it is necessary to only create an instant need, e.g., database connection. You can only create an instance when the connection is closed or ensure to close the open instance before you open a new one. This pattern is also called the strict pattern. A disadvantage of this pattern is its terrible experience in testing because of its hidden objects that are not easy to select for testing.
Factory Pattern
It is creational, and it creates things without the need for a constructor. It offers a generic object creation interface through which we can specify the factory object type to be created. So, we specify the object, and the factory returns it immediately and sends it back to us for use. It is advisable to utilize the factory pattern when the configured object component has a high complexity level and when we want to easily create different object scenarios depending on our current environment. In addition, we can utilize the factory pattern when working with a lot of small objects that contain the same properties as you are creating objects that need to be decoupled.
Command Pattern
The command design pattern includes method invocations, operations, or applications in a single object so that we can run method calls using our discretion. The command design pattern lets us issue commands from anything that executes commands and instead delegate responsibility to various objects. These commands are represented in the formats run( ) and execute( ).
Constructor Design Pattern
This is a special method by which newly created objects are initiated as soon as the memory is allocated. Because JavaScript is usually object-oriented, it mainly deals with objects; therefore, it important to know about object constructors.
Prototype Pattern
The prototype pattern is based on the prototypical inheritance used to create objects to act as prototypes for other objects. In effect, prototypes serve as a blueprint for any object constructor created. It should be noted that prototype relationships can create problems with listing the properties of objects and also wrap the loop content into a hasOwnProperty( ) check. Object. create enables us to easily apply advanced concepts like differential inheritance, where objects can be inherited directly from other objects.
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Originally published at upstack.co on March 14, 2021, by Emmanuel Ighosewe.
