how to make a animation play only when I get into the range of that game object?

 i have a game object that is an enemy. I want its animation to play only when I get really close to it.(im controllled by a fps player controller in my game) 

var rayCastLength = 5;

function Update () { var hit : RaycastHit;

//check if were in range... 

if(

Physics.Raycast(transform.position, transform.forward, hit, rayCastLength))

 { // ... 

with the object if(hit.collider.gameObject.tag == "lift_door") 

{

 //play the animation: hit.collider.gameObject.animation.Play("lift_door_open"); 

} 

}



}