Using most recent data from Node server upon page load

When my page gets requested, I have my server get data from a database. I've got that part figured out using an express route. Now I obviously want to use that data when generating the page. How do I do this?

    app.get('/', function(req, res) {
        console.log("GET REQUEST RECEIVED")
        getData().then(function(result) {
        data = result;
        }, function(err) {
        console.log(err);
        });
    //useDataInAppJs(data); ??????????????????????????
        res.sendfile(__dirname + '/public/index.html')
    })

I've been Googling a lot but just can't seem to figure out how to implement that commented line.