Documentation for "update" at:

http://mongodb.github.io/node-mongodb-native/markdown-docs/insert.html

...says callback takes two parameters. In fact, it takes three (when

). This makes a difference when running with an async library such as caolan/async.

The attached go.js shows the JSON representation of the third parameter ("something"):

n: 1
something: {
"updatedExisting": true,
"n": 1,
"connectionId": 88,
"err": null,
"ok": 1
}
dummy: undefined