Here is a simple example with comments:

 class EControl
 {

    // This is the singleton instance that is shared with everyone.
    private static var Instance : EControl;

    // Everything that needs to get the singleton
    // instance, calls this function to get it.
    public static function GetInstance() : EControl
    {
        if (Instance == null)
            // This is the first time the function was called.  Need to
            // construct the shared instance.
            Instance = new EControl();
        return Instance;
    }

     var state : boolean ;

     // Private constructor.  This is what forces the class
     // to be a singleton since the only way to construct it
     // is via GetInstance().
     // NOTE:  Private constructors are not normally allowed
     // in JavaScript.  But it is OK in Unity.
     private function EControl()
     {
        state=false;
     }

     function GetState() : boolean
     {
       return state;
     }

}

You get instances of the singleton as follows:

private var control : EControl;

function Start() 
{
    control = EControl.GetInstance();
    Debug.Log(control.GetState());
    // The next line would cause a compile time error due to
    // the constructor's protection level.
    // control = new EControl();
}