Cached fibonacci

fib.js

var http = require('http');

function fib(n){                                                                              
    if (n < 2) return 1;
    else return fib(n-2) + fib(n-1);
}

var cached_fib = (function(){
    var cache = {};
    return function(n) {
        if (cache[n]) return cache[n];
        else return cache[n] = fib(n);
    }
})();

var server = http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end(cached_fib(40).toString());
}).listen(3000);