Stamp Duty Calculator

gistfile1.js

var range = {
  0: { min: 0, max: 125000},
  2: { min: 125000, max: 250000},
  5: { min: 250000, max: 925000},
  10: { min: 925000, max: 1500000},
  12: { min: 1500000, max: null}
};

function stampDuty(houseValue) {
  return Object.keys(range).reduce(function(duty, percentage) {
    var r = range[percentage];
    var rangeVal = 0;
    
    if (houseValue < r.min) {
      return duty;
    }
    
    if ((houseValue > r.min && houseValue <= r.max) || r.max === null ) {
      rangeVal = houseValue - r.min;
    } else if (houseValue > r.max) {
      rangeVal = r.max - r.min;
    }
    
    return duty += rangeVal * (percentage / 100);;
  }, 0);
}