How would I add a cool down time to my gun?

Unity Engine
1

I don’t know how to add one, can someone show me please?

var projectile : Rigidbody;
var speed = 20;

function Update () {

if ( Input.GetButton ("Fire1")) {

clone = Instantiate(projectile, transform.position, transform.rotation);
clone.velocity = transform.TransformDirection( Vector3 (0, 0, speed));

Destroy (clone.gameObject, 3);

}}
2

So, after you fire, there is a delay before you can fire again?

If so, just use a bool.

if (coolingDown)
return;

///fire gun code
coolingDown = true;
Invoke("gunCooledDown", 1);