Strategy Pattern in JavaScript (Live Playground)

The Strategy pattern is a behavioral design pattern that enables you to define a family of algorithms, encapsulate them within separate classes, and make them interchangeable at runtime. This pattern promotes maintainability and flexibility in your code by allowing you to switch between different algorithms without modifying the client code. In this tutorial, we'll explore the Strategy pattern in JavaScript, including its use cases, implementation, and benefits.

Why Use the Strategy Pattern?

The Strategy pattern is useful when you want to:

1. Implement a set of related algorithms that can be used interchangeably.
2. Decouple algorithm implementation from the client code.
3. Improve code maintainability by encapsulating algorithm logic within separate classes.

Implementing the Strategy Pattern in JavaScript

Here's an example of how to implement the Strategy pattern using JavaScript classes:

TypeScript

// Strategy interface
class Strategy {
  execute() {}
}

// Concrete strategies
class ConcreteStrategyA extends Strategy {
  execute() {
    console.log('Executing strategy A');
  }
}

class ConcreteStrategyB extends Strategy {
  execute() {
    console.log('Executing strategy B');
  }
}

// Context class
class Context {
  constructor(strategy) {
    this.strategy = strategy;
  }

  setStrategy(strategy) {
    this.strategy = strategy;
  }

  executeStrategy() {
    this.strategy.execute();
  }
}

// Client code
const strategyA = new ConcreteStrategyA();
const strategyB = new ConcreteStrategyB();

const context = new Context(strategyA);

context.executeStrategy(); // Output: Executing strategy A

context.setStrategy(strategyB);
context.executeStrategy(); // Output: Executing strategy B

In this example, the Strategy class represents the strategy interface, and ConcreteStrategyA and ConcreteStrategyB are concrete strategy classes. The Context class manages the current strategy and delegates algorithm execution to the strategy classes. The client code creates a context object with an initial strategy and invokes its executeStrategy method.

Live Playground, Try it Yourself

Benefits of the Strategy Pattern

Implementing the Strategy pattern in your JavaScript projects offers several benefits:

1. Maintainability: The Strategy pattern encapsulates algorithm logic within separate strategy classes, making your code more maintainable and easier to modify.
2. Flexibility: The Strategy pattern allows you to easily switch between different algorithms at runtime, providing flexibility in handling various scenarios.
3. Decoupling: The Strategy pattern decouples algorithm implementation from the client code, making your code cleaner and more modular.

Conclusion

In summary, the Strategy pattern is a valuable tool in JavaScript development that can help you create maintainable, flexible code. By understanding and implementing this pattern, you can enhance your web development skills and create more robust applications.