Scaling between two number ranges

Question

I remember using an equation to do this at some point – how do you do this in Javascript?

Plugin two number ranges:

rangeX = 1 (through) 10;
rangeY =         


        

Answer 1

No guarantees on the math, but I think something like this:

var xLow = 1;
var xHigh = 10:
var yLow = 300.77;
var yHigh = 559.22;

var inputY = 328.17;
var ouputX = xLow;

var scaleYOverX = (yHigh - yLow)/(xHigh - xLow);

if(inputY >= yLow && inputY <= yHigh) {
  outputX = (inputY - yLow)/scaleYOverX + xLow;
  alert(outputX);
} else {
  alert("Invalid input for Y scale");
}