How are the timeout IDs allocated?

One more question because this is driving me nuts and I can't find the reason why ledTimer gets incremented at all.

What happens when I clearTimeout(ledTimer) ? Is it set to an empty function so that when it comes to the given time it does nothing, or is it really removed?

Also when I add console.log(process.memory()); at the beginning of watch function then it shows memory usage goes up quite a lot when I press the button before the timeout passed.

The output now looks like that:

{"free":1722,"usage":78,"total":1800,"history":44,"stackEndAddress":536909512,"flash_start":134217728,"flash_binary_end":134432224,"flash_code_start":134443008,"flash_length":262144}
before: null
after: 2
{"free":1695,"usage":105,"total":1800,"history":44,"stackEndAddress":536909512,"flash_start":134217728,"flash_binary_end":134432224,"flash_code_start":134443008,"flash_length":262144}
before: null
after: 4
{"free":1695,"usage":105,"total":1800,"history":44,"stackEndAddress":536909512,"flash_start":134217728,"flash_binary_end":134432224,"flash_code_start":134443008,"flash_length":262144}
before: null
after: 6
>