Factory Pattern

The Factory Pattern is a creational design pattern that provides an interface for creating objects in a superclass but allows subclasses to alter the type of objects that will be created. It helps in managing and maintaining object creation in a clean and efficient way.

2.1 Definition

A Factory Pattern defines an interface for creating an object, but it is the responsibility of the implementing classes to instantiate the appropriate class.

2.2 Types of Factory Patterns

• Simple Factory
• Factory Method
• Abstract Factory

3.1 Simple Factory Example

class Shape {
    constructor(type) {
        this.type = type;
    }
}

class ShapeFactory {
    createShape(type) {
        return new Shape(type);
    }
}

// Usage
const factory = new ShapeFactory();
const circle = factory.createShape('Circle');
console.log(circle.type); // Circle

3.2 Factory Method Example

class Shape {
    draw() {}
}

class Circle extends Shape {
    draw() {
        return 'Drawing a Circle';
    }
}

class Square extends Shape {
    draw() {
        return 'Drawing a Square';
    }
}

class ShapeFactory {
    createShape(type) {
        if (type === 'Circle') {
            return new Circle();
        } else if (type === 'Square') {
            return new Square();
        }
        return null;
    }
}

// Usage
const factory = new ShapeFactory();
const shape1 = factory.createShape('Circle');
console.log(shape1.draw()); // Drawing a Circle
const shape2 = factory.createShape('Square');
console.log(shape2.draw()); // Drawing a Square