I'm trying to comunicate with a server, using XMLHttpRequest in javascript.

How can I pass info to the onload function?

```
// global variable that containts server response
var reply;

var makeRequest = function(extraInfo) {
  var request = new XMLHttpRequest();
  request.open(...);
  request.onload = handler;
};

var handler = function(data) {
  reply = data.target.response;
  console.log("Server Reply: " + reply);
};

```

How can I pass the parameter extraInfo from makeRequest to the handler function? (without using a global variable)