I would like to use CommonJS to include semantic-ui in my react jsx file. I installed semantic-ui with bower, and webpack is correctly configured to include the bower_components
As for the CSS you're going to want to load that in your index/whatever.html file before sourcing your JS.
Try the following before you require semantic-ui:
var $ = jQuery = require('jquery/dist/jquery.js');
window.jQuery = $; // Assure it's available globally.
var s = require('semantic-ui/dist/semantic-ui.js');
Not 100% sure this will work but it's worth a try.
Things can get tricky with CommonJS modules. Also, might be worth looking into React+Browserify. Makes it super simple to import NPM modules using require
.