Singleton Pattern

This pattern restricts instantiation of an object to a single reference thus reducing its memory footprint and allowing a "delayed" initialization on an as-needed basis. This isn't too common amongst JavaScript projects today but more common in WordPress.

Advantages

• Reduced memory footprint
• Single point of access
• Delayed initialization that prevents instantiation until required

Disadvantages

• Once instantiated, they're hardly ever "reset"
• Harder to unit test and sometimes introduces hidden dependencies

Example

var mySingleton = ( function( window, undefined ) {

  var instance = null;

  // revealing module pattern that handles initialization of our new module
  function initializeNewModule() {

    function myMethod() {
      alert( 'my method' );
    }

    function myOtherMethod() {
      alert( 'my other method' );
    }

    return {
      someMethod : myMethod,
      someOtherMethod : myOtherMethod
    };

  }

  // handles the prevention of additional instantiations
  function getInstance() {
    if( ! instance ) {
      instance = new initializeNewModule();
    }
    return instance;
  }

  return {
    getInstance : getInstance
  };

} )( window );

// example usage
mySingleton.getInstance().someMethod(); // alerts "my method"
mySingleton.getInstance().someOtherMethod(); // alerts "my other method"