What is Factory design pattern?

Creates objects without specifying exact class.

Problem

javascript

// Direct instantiation - inflexible
const circle = new Circle(5);
const square = new Square(10);

Solution - Simple Factory

javascript

class ShapeFactory {
  static createShape(type, ...args) {
    switch(type) {
      case 'circle':
        return new Circle(...args);
      case 'square':
        return new Square(...args);
      case 'triangle':
        return new Triangle(...args);
      default:
        throw new Error('Unknown shape');
    }
  }
}

// Usage
const shape1 = ShapeFactory.createShape('circle', 5);
const shape2 = ShapeFactory.createShape('square', 10);

Real Example - User Roles

javascript

class UserFactory {
  static createUser(role, data) {
    switch(role) {
      case 'admin':
        return new AdminUser(data);
      case 'moderator':
        return new ModeratorUser(data);
      case 'regular':
        return new RegularUser(data);
      default:
        return new GuestUser(data);
    }
  }
}

// Usage
const admin = UserFactory.createUser('admin', { name: 'John' });
admin.deleteUser(); // Only admin can do this

Benefits

✅ Flexibility ✅ Encapsulation ✅ Single place for creation logic ✅ Easy to extend

Short Answer

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Practice Problems

What is Factory design pattern?

#Problem

#Solution - Simple Factory

#Real Example - User Roles

#Benefits

Short Answer

Problem

Solution - Simple Factory

Real Example - User Roles

Benefits