node.js - How do I measure the execution time of JavaScript code with callbacks?

#short
#javascript
#profiling
for(var i = 1; i LIMIT; i++) {
var user = {
id: i,
name: "MongoUser [" + i + "]"
};
if(err || !saved) {
} else {
}
});
}

How can I measure the time taken by these database insert operations? I could compute the difference of date values after and before this piece of code but that would be incorrect because of the asynchronous nature of the code.