Router in a tweet

router.js

function(b,d,a,c){(onhashchange=function(){for(a in b)if(c=RegExp("^#?"+a+"$").exec(location.hash))return d(b[a].apply(0,c.slice(1)))})()}

test.js

var router = function(b,d,a,c){(onhashchange=function(){for(a in b)if(c=RegExp("^#?"+a+"$").exec(location.hash))return d(b[a].apply(0,c.slice(1)))})()}

// replace hashes with HTML5 history
function useNiceUrls () {
  if (history.replaceState && location.hash[1] === '/') {
    history.replaceState(0, 0, location.origin + location.hash.slice(1))
  }
}

// render page with layout
function render (page) {
  useNiceUrls()
  document.body.innerHTML = `
  <code>
    <ul>
      <li><a href="#">homepage</a></li>
      <li><a href="#/hello">simple route</a></li>
      <li><a href="#/hello/world">route with parameters</a></li>
      <li><a href="#/404">page not found</a></li>
    </ul>
    <p>${page}</p>
    <p>URL: ${location}</p>
  </code>
  `
}

router({
  '': () => `<b>Source code:</b><br>${router}`,
  '/hello': () => `Hello.`,
  '/hello/([^/]+)': (name) => `Hello ${name}.`,
  '.*': () => `Error #404.`
}, render)