Inject common scripts into the browser

inject.js

((global) => {
  var dict = {
    ramda: '//cdnjs.cloudflare.com/ajax/libs/ramda/0.23.0/ramda.min.js',
    rxjs: 'https://unpkg.com/@reactivex/rxjs/dist/global/Rx.js',
    'lodash/fp': 'https://cdn.jsdelivr.net/g/lodash@4(lodash.min.js+lodash.fp.min.js', // Exposed as `_`
  };

  // Returns the script tag
  global.inject = (src) => {
    var script = document.createElement('script');
    script.src = dict[src] || src; // Can manually inject any URL if its not found in dict
    return document.body.appendChild(script);
  };
})(window);