bidirectional declarative microrouter (ES6)

router.js

'use strict';

import {first, rest, last, trimLeft, partial, partialRight, omit, dropRight,
        zipObject, isObject, assign, ary, map, template} from 'lodash';

const placeHolderRegex = /:([a-zA-Z_][a-zA-Z0-9_]*)/g;

var trimLeadingColon = ary(partialRight(trimLeft, ':'), 1);

function assembleRoute(segment, routes) {
    var renderPath = template(segment, {interpolate: placeHolderRegex});
    return assign(renderPath, assemble(routes || {}, segment))
}

function assemble(routes, prefix = '') {
    return zipObject(map(routes, (val, key) => {
        let name = isObject(val) ? val.name : val;
        return [name, assembleRoute(prefix + key, isObject(val) ? val.routes : null)];
    }));
}

function match(routes, path) {
    for (var segment in routes) {
        if (!routes.hasOwnProperty(segment)) continue;
        let spec = routes[segment];
        let name = isObject(spec) ? spec.name : spec;
        let payload = isObject(spec) ? omit(spec, ['name', 'routes']) : {};
        let subRoutes = isObject(spec) ? spec.routes : null;
        let paramKeys = (segment.match(placeHolderRegex) || []).map(trimLeadingColon);
        let re = new RegExp('^' + segment.replace(placeHolderRegex, '([^/]+)') + '(/.+)?$');
        let matched = path.match(re);
        if (matched) {
            let remainingPath = last(matched);
            let params = zipObject(paramKeys, dropRight(rest(matched)));
            if (subRoutes && remainingPath) {
                let subMatch = match(subRoutes, remainingPath);
                if (subMatch) {
                    let [subName, subParams, subRemaining, subPayload] = subMatch;
                    return [[name].concat(subName), assign(params, subParams), subRemaining, subPayload];
                }
            }
            return [[name], params, remainingPath, payload];
        }
    }
    return null;
}

export default function(routes) {
    let router = assemble(routes);
    function resolve(path) {
        let matched = match(routes, path);
        if (matched) {
            let [keys, params, remaining, payload] = matched;
            let route = keys.reduce((obj, key) => obj[key], router);
            let result = {params, remaining, route, name: keys.join('.')};
            return isObject(payload) ? assign(payload, result) : result;
        }
        return null;
    }
    return assign(resolve, router);
}

sample.js

import router from './router';

let route = router({
  '/blub': { // key is the path to match
    name: 'blub', // must have name for bidirectional routing (must be unique among siblings)
    myValue: blub, // properties other than "name" and "routes" are for user data
    routes: { // "routes" property contains nested subroutes. can nest infinitely.
      '/edit/:id': { // can use placeholders to capture params
        name: 'edit',
        myValue: blubEdit
      }
    }
  },
  '/edit/:foo': {
    name: 'edit',
    myValue: edit
  }
});

route.blub(); // => "/blub"
route.blub.edit({id: 42}); // => "/blub/edit/42"
route.edit({foo: 'bar'}); // => "/edit/bar"

route('/blub'); // => {myValue: blub, params: {}, name: 'blub', remaining: ''}
route('/blub/edit/23'); // => {myValue: blubEdit, params: {id: '23'}, name: 'blub.edit', remaining: ''}
route('/edit/bar'); // => {myValue: edit, params: {foo: 'bar'}, name: 'edit', remaining: ''}

route('/blub/blah'); // => {... name: 'blub', remaining: '/blah'}
route('/blub/edit/23/foo/bar'); // => {... name: 'blub.edit', params: {id: '23'}, remaining: '/foo/bar'}

route('/blubb'); // => null
route('/edit/bar/'); // => null
route('/foo'); // => null

// captured params will all be merged into one object
router({
  '/get/:what/:id': {
    name: 'foo',
    routes: {
      '/bar/:barId': 'bar'
    }
  }
})('/get/foo/42/bar/23'); // => {... params: {what: 'foo', id: '42', barId: '23'}, name: 'foo.bar' }

// child route params overwrite parents
router({
  '/foo/:id': {
      name: 'foo',
      routes: {
        '/bar/:id': 'bar'
      }
  }
})('/foo/1/bar/2'); // => {... params: {id: '2'}, name: 'foo.bar' }