Express: Pretty print json output

I could swear that res.send and res.json would pretty-print the output as default when I used it before. However, I can't seem to get it to work this time. I also read that app.locals.pretty=true; should do it as well, but I can't seem to get it to work.

Here's some sample code:

var express = require('express'); var app = express();

var sample_data ={
        widget: {
                child: {
                        title: "Sample Konfabulator Widget",
                        name: "Das Widget",
                }
        } };

app.locals.pretty = true;

app.get('/pretty', function(req, res){
        res.json(sample_data); });



var port = process.env.PORT || 4000;

app.listen(port, function(){
        console.log('Listening on port ' + port); });