Factory Functions & Singleton Pattern

What design principle does this factory function follow?

const createGameEntity = (name, type) => {
  // Base entity with common properties
  const entity = {
    name,
    type,
    id: Math.random().toString(36).substr(2, 9),
    createdAt: new Date()
  };
  
  // Add type-specific properties and methods
  if (type === 'player') {
    return {
      ...entity,
      health: 100,
      inventory: [],
      attack(target) { /* implementation */ }
    };
  } else if (type === 'enemy') {
    return {
      ...entity,
      health: 50,
      damage: 10,
      attack(target) { /* implementation */ }
    };
  } else if (type === 'item') {
    return {
      ...entity,
      value: 15,
      use() { /* implementation */ }
    };
  }
  
  // Default case
  return entity;
};

Encapsulation
Composition over inheritance
This factory function follows the composition over inheritance principle: 1) It uses object composition to build entities with different capabilities, 2) It avoids deep inheritance hierarchies by adding specific properties directly, 3) It creates objects that only have the properties they need, 4) It's more flexible than class inheritance as it can mix and match features, 5) Different entity types can share some behavior while differing in others, 6) This approach is favored in JavaScript for its flexibility and simplicity.
Single responsibility principle
Interface segregation

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