The Tip That Didn't Add Up — JavaScript Bug Hunt

Briefing

Inspired by the gig-economy payout scandals over vanishing cents: split a $1.00 tip among 3 drivers with floor(total/n) and one cent simply evaporates — times millions of orders.

split.js must conserve every cent: parts differ by at most one, extra cents go to the earliest parts, and the sum is exact.

Bug report

BUG-1CENT-TIP · Priority: High (press risk) · Reported by: payouts

splitEvenly(totalCents, n):

• returns n integers summing EXACTLY to totalCents
• parts differ by at most 1; earlier parts get the extra cents

Observed: splitEvenly(100, 3) -> [33, 33, 33]. One cent gone, every order.

Logs

[payout] reconciliation: -$8,214.66 this quarter in vanished remainders

The code as shipped

src/pay/split.js (editable)

// Splits a tip evenly across n recipients.
exports.splitEvenly = function (totalCents, n) {
  var each = Math.floor(totalCents / n);
  var out = [];
  for (var i = 0; i < n; i++) {
    out.push(each);
  }
  return out;
};