Contains an example of a singleton

SingletonDemo.js

// Create a closure
var SecretStore = (function() {
  var data, secret, newSecret;
 
  // Emulation of a private variables and functions
  data = 'secret';
  secret = function() {
    return data;
  }
  newSecret = function(newValue) {
    data = newValue;
    return secret();
  }
 
  // Return an object literal which is the only way to access the private data.
  return {
    getSecret: secret,
    setSecret: newSecret,
  };
})();
 
var secret = SecretStore;
 
// => "secret"
console.log(secret.getSecret());
 
// => "foo"
console.log(secret.setSecret("foo"));
 
// => "foo"
console.log(secret.getSecret());
 
var secret2 = SecretStore;
 
// => "foo"
console.log(secret2.getSecret());