Regex Router

router.js

/*
Routing consists of matching a string against a set of regular expressions to call a function.
In this case, we can define routes as an array of regular expressions and callbacks.
For example:
let routes = [
    [/^\/user\/(\d+)\/?$/, (id) => response({id})],
    [/^\/user\/([a-z0-9-_]+)\/?$/, (name) => response({name})],
    [/^\/user\/([a-z0-9-_]+)\/(\d+)\/?$/, (name, id) => response({id, name})],
];

If needed, we can provide our own procedures for converting user-supplied routes into regular expressions.
We can also provide some post-processing to convert regex results to the proper types by wrapping each callback in a decorator
*/

const router = routes => route => {
  for (let i = 0; i < routes.length; i ++) {
      let [regex, callback] = routes[i];
      let match = route.match(regex);
      if (match) {
        return callback.apply(null, match.slice(1));
      };
  }
}

// usage: let r = router(routes); r('/user/john/100');