Simple RegExp-based Router

example.js

// "Routes"
function Home() {
    console.log('Home')
}

function Products(params) {
    console.log(params.category, 'products')
}

function ProductDetails(params) {
    console.log('Product #' + params.id)
}

function NotFound() {
    console.log('Not found :(')
}

var router = new Router()
router.add('/', Home)
router.add(/^\/products\/([0-9]+)$/, ProductDetails, 'id')
router.add('/products/:category', Products)
router.add('*', NotFound)

console.log(router.match('/'))
console.log(router.match('/products/sports'))
console.log(router.match('/products/123'))
console.log(router.match('/nope'))

router.js

'use strict';

function Router(routes) {
  this.routes = routes || []
}

Router.prototype.add = function(pattern, handler) {
  var route = {
    names: [],
    handler: handler
  }

  if (pattern instanceof RegExp) {
    route.pattern = pattern
    route.names = Array.prototype.slice.call(arguments, 2)
  } else if (typeof pattern == 'string') {
    route.pattern = new RegExp('^' + pattern.replace(/\*/g, '(.*)').replace(/(?::([^\/]+))/g, function(match, name) {
      route.names.push(name)

      return '([^\/]+)'
    }) + '$')
  } else {
    route = pattern
  }

  this.routes.push(route)

  return route
}

Router.prototype.match = function(url) {
  for (var i = 0, l = this.routes.length; i < l; i++) {
    var route = this.routes[i]

    var matches = route.pattern.exec(url)

    if (matches) {
      var names = route.names,
          params = {}

      for (var j = 0, k = names.length; j < k; j++) {
        params[names[j]] = matches[j + 1]
      }

      return {
        params: params,
        handler: route.handler
      }
    }
  }
}