Instantiate Script Not Working

Here's what the script is doing:

• 'counter' variable is created and set to 0

• while loop is hit, checking if 'counter' is greater than 20. 'counter' is 0 so it skips the loop

• 'counter' is incremented by one

• Update ends and 'counter' variable is removed

• repeat every frame

I'm guessing this is what you intended to do (Note: I normally write in C#, so if there's a JS syntax error I apologize):

 var floor : GameObject;
 function Start () //Runs once at start of game
 {
      var counter : int = 0;
      while (counter < 20)
      {
           Instantiate(floor, new Vector3(counter, -1, 0, Quaternion.identity);
           counter += 1;
      }
 }