Expand Ratios

ratios.js

// https://stackoverflow.com/questions/14224535/scaling-between-two-number-ranges

function withinRange(val, { min, max }) {
  return (
    val > max
        ? max
        : val < min
          ? min
          : val
  );
}

function ratioToValue(ratio, { min, max }) {
  const value = ratio * (max - min) + min;

	return withinRange(value, { min, max });
}

function valueToRatio(value, { min=0, max=1 }={}) {
  const ratio = (value - min) / (max - min);

  return withinRange(ratio, { min: 0, max: 1 });
}

console.log(
	valueToRatio(1, { min: 1, max: 3 })
)