Express 4 redirect www.domain.com to domain.com

redirect.js

express.use(function(req,res,next){
        var host = req.get('host');
        if(/^www\./.test(host)){
            host = host.substring(4, host.length);
            res.writeHead(301, {'Location':req.protocol + '://' + host + req.originalUrl,
                'Expires': new Date().toGMTString()});
            res.end();
        } else {
            next();
        }
    });

Use this as the first middleware.