How to include masonry in app.js using gulp?

I am using gulp to mix my scripts etc. Now I am wondering if I need to include masonry in my app.js to get it working in the project. The instructions tell to include <script src="/path/to/masonry.pkgd.min.js"></script> in the site however doing like that It won't be mixed in app.js. So my question is how do you include it? I was thinking something like: window.Masonry = require('masonry-layout'); in bootstrap.js but obviously I am not sure. Any clue?