express/node app stops listening after a few requests

what I'm trying to achieve is to accept requests for a value, add that value to an array, run a function on it that'll query it and then remove it from the array with the shift function. What I have so far is a simplified framework of that, but it's now giving me this error.

RangeError: Maximum call stack size exceeded

if there's anything I can do to improve my code as well please let me know.

app.js

 var express    = require('express')
 , http         = require('http')
 , path         = require('path')
 , fs           = require('fs')
 , eventEmitter = require('events').EventEmitter;

 var app = express();

 app.configure(function(){
 app.set('port', process.env.PORT || 3000);
 app.set('views', __dirname + '/views');
 app.set('view engine', 'jade');
 app.use(express.favicon());
 app.use(express.logger('dev'));
 app.use(express.bodyParser());
 app.use(express.methodOverride());
 app.use(app.router);
 app.use(express.static(path.join(__dirname, 'public')));
 });

 var ee = new eventEmitter;
 var queries = new Array();
 ee.on('next', next_search); 

 function next_search() {
console.log(queries);
search();
 }

 function search() {
    // do something
queries.shift();
console.log(queries);
    ee.emit('next') 
 }

 app.get('/', function (req, res) {
    res.sendfile(__dirname + '/index.html');
 });

 app.post('/search', function(req, res) {
letter = req.param('letter');
console.log(letter);
queries.push(letter);
next_search();
 });

 http.createServer(app).listen(app.get('port'), function(){
    console.log("Express server listening on port " + app.get('port')); 
 });

jQuery code

 $(document).ready(function() {
     $('#letter').on("keyup", function() {
      letter = $('#letter').val();
      $.post("/search", { letter: letter}, function(data) {
    $('#status').html(data);
          });
 });
 });