Can't get list to work (simple)

Hey out there. I am trying to learn how to use lists in js.

I have

var thing1 = new List.<GameObject>();
  var thing2 = new List.<GameObject>();

but I get this error message

ssets/My scripts/tryout.js(119,17): BCE0005: Unknown identifier: ‘List’.

what’s wrong? I’m not finding any clear instructions anywhere that explain for js

You need the following at the top of the file:

import System.Collections.Generic;