Javascript / jQuery - map a range of numbers to another range of numbers

Question

In other programming languages such as processing, there is a function which allows you to convert a number that falls within a range of numbers into a number within a diffe

Answer 1

If your range always starts from 0 then all you have to do is

mouseValue * range.max / screen.max

---

A more involved any-range to any-range conversion would require

function convertToRange(value, srcRange, dstRange){
  // value is outside source range return
  if (value < srcRange[0] || value > srcRange[1]){
    return NaN; 
  }

  var srcMax = srcRange[1] - srcRange[0],
      dstMax = dstRange[1] - dstRange[0],
      adjValue = value - srcRange[0];

  return (adjValue * dstMax / srcMax) + dstRange[0];

}

Use like convertToRange(20,[10,50],[5,10]);