Takes a numeric value 'x' and it's current scale as min / max, and converts it to a scale with a different min / max.

convert.js

(function() {
	function convertScale(x, min, max, min2, max2) {
		var distance, percent;
		distance = max - min;
		percent = (x - min) / distance * 100;
		percent = percent > 0 ? percent : -percent;
		distance = max2 - min2;
		return distance * percent / 100;
	};
)();