prototype methods vs defined function (version: 0)
Testing performance: multiple prototype methods chained after one another that invoke a function from a external source (like fs.readDir or fs.stat, but in this case onTodo1 and onTodo2) - VS - one prototype method that creates a new function in the scope of that one method every time the method is called.
Comparing performance of: Chaining multiple prototype Methods vs One prototype method
Memory measurements supported only in Chrome.
For precise memory measurements Chrome must be launched with --enable-precise-memory-info flag.
More information: Monitoring JavaScript Memory