You can access the current url quite easily in JavaScript with window.location
You have access to the segments of that URL via this locations
object. For example:
// This article:
// https://stackoverflow.com/questions/21246818/how-to-get-the-base-url-in-javascript
var base_url = window.location.origin;
// "http://stackoverflow.com"
var host = window.location.host;
// stackoverflow.com
var pathArray = window.location.pathname.split( '/' );
// ["", "questions", "21246818", "how-to-get-the-base-url-in-javascript"]
In Chrome Dev Tools, you can simply enter window.location
in your console and it will return all of the available properties.
Further reading is available on this Stack Overflow thread