将参数从jade发送到js/node

我正在尝试将变量从follower/jade传递到js/node文件。我正在使用node+express+follower+js我按照以下方式做，但我没有得到价值观。这是我正在使用的代码：

app.js

var express = require('express');
var routes = require('./routes');
var tiles = require('./routes/tiles');
var http = require('http');
var path = require('path');
var app = express();
app.set('port', process.env.PORT || 3000);
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
app.use(express.favicon());
app.use(express.logger('dev'));
app.use(express.json());
app.use(express.urlencoded());
app.use(app.router);
app.use(express.static(path.join(__dirname, 'public')));
if ('development' == app.get('env')) {
  app.use(express.errorHandler());
}
app.get('/', routes.index);
app.get('/tiles', tiles.tiles);
http.createServer(app).listen(app.get('port'), function(){
  console.log('Express server listening on port ' + app.get('port'));
});

index.js//呈现index.jade文件的索引文件

exports.index = function(req, res){
  res.render('index');
};

index.jade//在jade文件中，我发送params的行是"tiles？z={z}&x={x}&y={y}"

doctype html
html
  head
    title Tile Server Example
    meta(charset='utf-8')
    meta(name='viewport', content='width=device-width, initial-scale=1.0')
    link(rel='stylesheet', href='http://cdn.leafletjs.com/leaflet-0.7.1/leaflet.css')
  body
     #map(style='width: 800px; height: 800px')
     a(href='tiles') < tiles >
    script(src='http://cdn.leafletjs.com/leaflet-0.7.1/leaflet.js')
  script.
    var map;
    var mbTiles = new L.tileLayer('tiles?z={z}&x={x}&y={y}', {
    tms: true,
    attribution: 'this is a test',
    opacity: 0.7
    });
    map = new L.Map("map",{
    zoom: 18,
    center: [12.83563,77.68312],
    layers: [mbTiles]
    }); 

tiles.js//这里是我获取参数的地方，我通过控制台显示它们

 var x = "", y = "", z = "";
module.exports = function(req, res){    
    x = req.query.x; 
    y = req.query.y;
    z = req.query.z;    
    console.log("z="+z+"&x="+x+"&y="+y);
    var sqlite3 = require('sqlite3').verbose();
    var db = new sqlite3.Database('routes/tiles.mbtiles');
    var sql = "SELECT * FROM tiles WHERE zoom_level = "+z+" AND tile_column = "+x+" AND tile_row = "+y;
    db.each(sql, function(err, row) {
            console.log(sql);
            res.writeHead(200, {'content-type':'image/jpg'});
            res.write(row.tile_data);
            res.end();
    }); 
    db.close();
};

知道吗？