Singleton Design Pattern using TypeScript

The Singleton design pattern ensures that a class has only one instance and provides a global point of access to it. This pattern is useful when you want to limit the number of instances of a class to one.

Here’s an example of the Singleton design pattern implemented in TypeScript:

class Singleton {
  // Holds the single instance of the class
  private static instance: Singleton;

  // Private constructor ensures the class can't be instantiated from outside
  private constructor() {
    // Initialize any properties here
  }

  // Static method to provide access to the single instance
  public static getInstance(): Singleton {
    if (!Singleton.instance) {
      Singleton.instance = new Singleton();
    }
    return Singleton.instance;
  }

  // Example method for demonstration
  public showMessage(): void {
    console.log("Hello from the Singleton instance!");
  }
}

// Usage
const singleton1 = Singleton.getInstance();
const singleton2 = Singleton.getInstance();

// Output: Hello from the Singleton instance!
singleton1.showMessage(); 

// Output: true (Both are the same instance)
console.log(singleton1 === singleton2);

Applications

The Singleton design pattern is commonly used in scenarios where you need to ensure that a class has only one instance, such as: