Help requiring modules on Espruino-wifi board.

I have tried a few ways to put a module in my local project. In the web ide I have set a folder for a project, this created a bunch of folders, one of them modules - I have tried to NPM install a module gsap there but I cannot require this with:

var gsap = require('gsap');

I thought maybe it doesn't need to be in node_modules folder so I took out the gsap folder and only that is in modules, still can't find it.

I copied the min.js file to modules folder, still cannot require it there.

Both of these examples work if I use the cmd to run node and the require('gsap'). What is the correct way to require a module from modules folder in a project?