Karim Aya

Karim Aya

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7 Best JavaScript Design Patterns You Should Know

In this tutorial, I'll explore seven best and most popular JavaScript design patterns, which of course most of them will fall under three categories namely; creation design patterns, structural design patterns and behavioral design patterns. 

Design patterns in JavaScript are reusable solutions applied to commonly occurring problems in writing JavaScript web applications.

1. Constructor Design Pattern

2. Prototype Pattern

3. Module Design Pattern

4. Singleton Pattern

5. Factory Pattern

6. Observer Pattern

7. Command Pattern

Read Also: JavaScript Cheatsheet - Comprehensive PDF Included

Introduction

It is quite appropriate to refer JavaScript design patterns as templates to provide solutions to problems but not quite to say that these patterns can replace the developers.

Design patterns help combine experiences of many developers to structure the codes in an optimized manner that meet the problems we are seeking solutions to, and gives common vocabulary used to describe solutions to our problems than describing the syntax and semantics of our code.

JavaScript design patterns assist developers to write organized, beautiful and well-structured codes. Although design patterns, when used can easily be re-used, they can never supplement developers, rather they only support them by preventing minor issues that could lead to major problems on the web application development by providing generalized solutions that are not tied to a specific problem.

They decrease the overall codebase by doing away with unnecessary repetitions, thus makes our code more robust than the ad-hoc solutions.

In this article, I will explore seven best and most popular JavaScript design patterns, which of course most of them will fall under three categories namely; creation design patterns, structural design patterns and behavioral design patterns. A pattern is something like the following image; just to acquaint you into the context.

1. Constructor Design Pattern.

This is a special method that is used to initialize the newly created objects once a memory is allocated. Since JavaScript is typically object-oriented, it deals with objects most, therefore I intend to delve in to object constructors. There are three ways to create new objects in JavaScript:

The following is one way to create a constructor design pattern.

// This creates a new empty Object

var newObject = {};

// This creates a new empty Object

var newObject = Object.create(Object.prototype);

var newObject = newObject();


To access the properties of a function, you need to initialize the object.

const object = new ConstructorObject();

Whereby the new keyword above tells JavaScript that aconstructorObjectshould act as a constructor. Inheritance is one thing this design pattern does not support. 

Read Also: 12 Concepts That Will Level Up Your JavaScript Skills

2. Prototype Pattern

The prototype pattern is based on prototypical inheritance whereby objects created to act as prototypes for other objects. In reality, prototypes act as a blueprint for each object constructor created.

Example

var myCat= {
name:"Ford Escort",
brake:function(){
console.log("Stop! I am applying brakes");
}
Panic : function (){
console.log ( "wait. how do you stop thuis thing?")
}
}
// use objec create to instansiate a new car
var yourCar= object.create(myCar);
//You can now see that one is a prototype of the other
console.log (yourCar.name);]


Read Also: 127 Useful JavaScript Snippets You Can Understand in 30 Seconds

3. Module Design Pattern

In the module design pattern, there is an improvement from the prototype pattern. The different types of modifiers (both private and public) are set in the module pattern. You can create similar functions or properties without conflicts. There is the flexibility of renaming functions publicly. The daunting part of this is the inability to override the created functions from the outside environment.

Example


function AnimalContainter () {

const container = [];

function addAnimal (name) {
container.push(name);
}

function getAllAnimals() {
return container;
}

function removeAnimal(name) {
const index = container.indexOf(name);
if(index < 1) {
throw new Error('Animal not found in container');
}
container.splice(index, 1)
}

return {
add: addAnimal,
get: getAllAnimals,
remove: removeAnimal
}
}

const container = AnimalContainter();
container.add('Hen');
container.add('Goat');
container.add('Sheep');

console.log(container.get()) //Array(3) ["Hen", "Goat", "Sheep"]
container.remove('Sheep')
console.log(container.get()); //Array(2) ["Hen", "Goat"]


Read Also: Top 35 JavaScript Shorthands for Beginners

4. Singleton Pattern

It is essential in a scenario where only one instance needs to be created, for example, a database connection. It is only possible to create an instance when the connection is closed or you make sure to close the open instance before opening a new one. This pattern is also referred to as strict pattern, one drawback associated with this pattern is its daunting experience in testing because of its hidden dependencies objects which are not easily singled out for testing.

Example

function DatabaseConnection () {

let databaseInstance = null;

// tracks the number of instances created at a certain time
let count = 0;

function init() {
console.log(`Opening database #${count + 1}`);
//now perform operation
}
function createIntance() {
if(databaseInstance == null) {
databaseInstance = init();
}
return databaseInstance;
}
function closeIntance() {
console.log('closing database');
databaseInstance = null;
}
return {
open: createIntance,
close: closeIntance
}
}

const database = DatabseConnection();
database.open(); //Open database #1
database.open(); //Open database #1
database.open(); //Open database #1
database.close(); //close database


Read Also: Top 10 JavaScript Array Methods You Should Know

5. Factory Pattern

It is a creational concerned with the creation of objects without the need for a constructor. It provides a generic interface for creating objects, where we can specify the type of factory objects to be created. Therefore, we only specify the object and the factory instantiates and returns it for us to use. It is wise for us to use factory pattern when the object component set up has a high level of complexity and when we want to create different instances of objects easily depending on the environment we are in. We can also use factory pattern when working with many small objects sharing the same properties and when composing objects that need decoupling.

Example


// Dealer A

DealerA = {};

DealerA.title = function title() {
return "Dealer A";
};

DealerA.pay = function pay(amount) {
console.log(
`set up configuration using username: ${this.username} and password: ${
this.password
}`
);
return `Payment for service ${amount} is successful using ${this.title()}`;
};

//Dealer B

DealerB = {};
DealerB.title = function title() {
return "Dealer B";
};

DealerB.pay = function pay(amount) {
console.log(
`set up configuration using username: ${this.username}
and password: ${this.password}`
);
return `Payment for service ${amount} is successful using ${this.title()}`;
};

//@param {*} DealerOption
//@param {*} config

function DealerFactory(DealerOption, config = {}) {
const dealer = Object.create(dealerOption);
Object.assign(dealer, config);
return dealer;
}

const dealerFactory = DealerFactory(DealerA, {
username: "user",
password: "pass"
});
console.log(dealerFactory.title());
console.log(dealerFactory.pay(12));

const dealerFactory2 = DealerFactory(DealerB, {
username: "user2",
password: "pass2"
});
console.log(dealerFactory2.title());
console.log(dealerFactory2.pay(50));


Read Also: Best JavaScript Frameworks, Libraries and Tools to Use

6. Observer Pattern

The observer design pattern is handy in a place where objects communicate with other sets of objects simultaneously. In this observer pattern, there is no unnecessary push and pull of events across the states, rather the modules involved only modify the current state of data.

Example

function Observer() {
this.observerContainer = [];
}

Observer.prototype.subscribe = function (element) {
this.observerContainer.push(element);
}

// the following removes an element from the container

Observer.prototype.unsubscribe = function (element) {

const elementIndex = this.observerContainer.indexOf(element);
if (elementIndex > -1) {
this.observerContainer.splice(elementIndex, 1);
}
}

/**
* we notify elements added to the container by calling
* each subscribed components added to our container
*/
Observer.prototype.notifyAll = function (element) {
this.observerContainer.forEach(function (observerElement) {
observerElement(element);
});
}

7. Command Pattern

To wrap up, I would say the command design pattern ends my 7 best sums of JavaScript design patterns. The command design pattern encapsulates method invocation, operations or requests into a single object so that we can pass method calls at our discretion. The command design pattern gives us an opportunity to issue commands from anything executing commands and delegates responsibility to different objects instead. These commands are presented in run() and execute() format.

(function(){

var carManager = {

//information requested
requestInfo: function( model, id ){
return "The information for " + model + " with ID " + id + " is foo bar";
},

// now purchase the car
buyVehicle: function( model, id ){
return "You have successfully purchased Item " + id + ", a " + model;
},

// now arrange a viewing
arrangeViewing: function( model, id ){
return "You have successfully booked a viewing of " + model + " ( " + id + " ) ";
}
};
})();

Read Also: 16 JavaScript Tricks You Should Know

Conclusion

It is beneficial for JavaScript developers to use design patterns. Some major advantages of using design patterns include project maintainability and also cuts off unnecessary work on the development cycle. Even though JavaScript design patterns can provide solutions to complex problems, needless to say, rapid development and productivity, it is improper to conclude that these design patterns can replace the developers.

#javascript #programming #js #designpatterns

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7 Best JavaScript Design Patterns You Should Know

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bindu singh

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Samanta  Moore

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Builder Design Pattern

What is Builder Design Pattern ? Why we should care about it ?

Starting from **Creational Design Pattern, **so wikipedia says “creational design pattern are design pattern that deals with object creation mechanism, trying to create objects in manner that is suitable to the situation”.

The basic form of object creations could result in design problems and result in complex design problems, so to overcome this problem Creational Design Pattern somehow allows you to create the object.

Builder is one of the** Creational Design Pattern**.

When to consider the Builder Design Pattern ?

Builder is useful when you need to do lot of things to build an Object. Let’s imagine DOM (Document Object Model), so if we need to create the DOM, We could have to do lot of things, appending plenty of nodes and attaching attributes to them. We could also imagine about the huge XML Object creation where we will have to do lot of work to create the Object. A Factory is used basically when we could create the entire object in one shot.

As **Joshua Bloch (**He led the Design of the many library Java Collections Framework and many more) – “Builder Pattern is good choice when designing the class whose constructor or static factories would have more than handful of parameters

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Giles  Goodwin

Giles Goodwin

1603184040

7 JavaScript Design Patterns Every Developer Should Know

A template for every project? Sounds amazing, isn’t it?

That’s also a level of coding I’m striving for.

One of the ways to achieve it is using design patterns, which help to write well-structured, beautiful, and organized codes.

In this story, we will discover some of the common design patterns used in JavaScript. Let’s get into it.

1. Constructor Pattern

You are familiar with constructors as functions that initialize objects with specific properties and methods.

The constructor pattern is similar to that definition. We use this pattern to create multiple instances of the same object.

There are many ways to create a new object in JavaScript. Take a look at the examples below:

// Using {} to create empty objects:
let person = {};

// Using Object() to create empty objects:
let person = new Object();
// Using function constructor:
function Person(name, age) {
  this.name = name;
  this.age = age;
  this.showName = () => console.log(this.name);
}
let person = new Person(‘Amy’, 28);
person.showName();

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Madyson  Reilly

Madyson Reilly

1602747125

JavaScript — Build your object a builder!

Design Patterns

Before we will go over the builder design pattern, let’s briefly go over design patterns in general.

What is a Design Pattern?

A design pattern is a general and reusable solution for common problems you may encounter when designing your software. Each design pattern solves a different problem and can be customized to your use case with much ease.

Why do we need them?

One of the main reasons we need design patterns is to make our software very changeable, so it will be maintainable and will support future changes.

All software programs have to change and modify or they will cease to exist. The amount of time we spend on maintaining a software program is bigger than the amount of time it takes us to develop the program.

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