SOLID Principles in JavaScript

What SOLID principle is being applied in this refactoring example?

// Before:
class OrderProcessor {
  constructor(order) {
    this.order = order;
  }

  processOrder() {
    if (this.order.type === 'physical') {
      // Process physical order
    } else if (this.order.type === 'digital') {
      // Process digital order
    }
  }
}

// After:
class OrderProcessor {
  constructor(orderStrategy) {
    this.orderStrategy = orderStrategy;
  }

  processOrder() {
    return this.orderStrategy.process();
  }
}

Interface Segregation Principle
Liskov Substitution Principle
Open/Closed Principle
This refactoring applies the Open/Closed Principle (OCP). Instead of modifying the OrderProcessor class each time a new order type needs to be supported, we inject an order processing strategy. The class is now closed for modification (we don't need to change its code) but open for extension (we can add new order processing strategies). This also demonstrates the Strategy pattern, which is often used to implement OCP.
Single Responsibility Principle

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