Testing -> https://twitter.com/FQ400/status/1014078551073517573

browser-url-parser.js

/*
  Access the global variable document
*/
const browserUrlParser1 = (url) => {
  const p = document.createElement('a');
  p.href = url;
  return p;
}

/*
  A default parameter that can be overwritten in tests
*/
const browserUrlParser2 = (url, doc=document) => {
  const p = doc.createElement('a');
  p.href = url;
  return p;
}

/*
  A function that returns a function 
*/
const createBrowserUrlParser = (doc) => (url) => {
  const p = doc.createElement('a');
  p.href = url;
  return p;
}
const browserUrlParser3 = createBrowserUrlParser(document);

/*
  Using object destructuring and default values
*/
const browserUrlParser4 = ({url, doc=document}) => {
  const p = doc.createElement('a');
  p.href = url;
  return p;
}