This is really just to satisfy curiosity, and see if there's a better way to do this.
On my Windows 8 box, Node's
It's built into node and called
Returns an array of objects containing information about each CPU/core installed: model, speed (in MHz), and times (an object containing the number of milliseconds the CPU/core spent in: user, nice, sys, idle, and irq).
The length of this array is the number of "processors" in the system. Most systems only have one CPU, so that's the number of cores of that CPU.