Reverse animation at the point it stopped playing

I want to have a animation play when a button is pressed down. And then have the animation reverse from the point it stopped when the button is released, how can i achive this using javascript?

Try this:

function Update () {
    if (Input.GetButton ("Fire2") {    
        animation.Play ("FunkyThing");
    }

    if (Input.GetButton ("Fire1") {
        animation["FunkyThing"].speed = -1.0;
    }
}

Play the animation with `right-click` or `ctrl`. To reverse the animation, press `spacebar` or `left-click`.