Singleton Pattern in TypeScript

Below is an awesome singleton pattern implementation I found deep in the bowels of StackOverflow using TypeScript (adapted from my favourite C# implementation).

This works well if you are wanting to create a single instance class for use through your application such as a logger or user service.

export class Logger {
  private static _instance:Logger = new Logger();

  constructor() {
    if(Logger._instance) {
      throw new Error("The Logger is a singleton class and cannot be created!");
    }

    Logger._instance = this;
  }

  public static getInstance() : Logger {
    return Logger._instance;
  }

  public trace(message: string) {
    console.log('[Trace] ' + message);
  }

  // ...
}

Using the Logger class is as simple as adding a line like this:

Logger.getInstance().trace("Hello world!")

… or more realistically:

this.logger = Logger.getInstance();

Happy coding :)