/// <summary>
 /// Constructs an instance of JS engine switcher
 /// </summary>
 public JsEngineSwitcher(JsEngineFactoryCollection engineFactories)
     : this(engineFactories, string.Empty)
 {
 }
 /// <summary>
 /// Constructs an instance of JS engine switcher
 /// </summary>
 public JsEngineSwitcher(JsEngineFactoryCollection engineFactories, string defaultEngineName)
 {
     EngineFactories   = engineFactories;
     DefaultEngineName = defaultEngineName;
 }
 /// <summary>
 /// Private constructor for implementation Singleton pattern
 /// </summary>
 private JsEngineSwitcher()
 {
     DefaultEngineName = string.Empty;
     EngineFactories   = new JsEngineFactoryCollection();
 }