Hotwire cutting

I'm considering to build a hot-wire foam cutter.
During my research into the amount of current required I stumbled upon a web page claiming that I should expect 1W for each inch of wire.

So I desided to make a javascript that could assist me in determining the corect current.

Resistance: [Ohm/m]
Distance per W: [cm/W]
Voltage: [V]

The proper way of driving a hot-wire cutter is using a constant current source, but I did't want to build one of those so the script also calculates the wire length that for a given voltage would give the correct wattage.