Map a Number from One Value System to Another

numberMap.js

Number.prototype.map = (istart, istop, ostart, ostop) => {
	return ostart + (ostop - ostart) * ((this - istart) / (istop - istart));
};

const map = (value, istart, istop, ostart, ostop) => {
	return ostart + (ostop - ostart) * ((value - istart) / (istop - istart));
};