Source Code

Every formula in Hearth runs in your browser. No server sees your data. The source tab inside the calculator shows the same functions documented here — both are kept in sync with score.ts.

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score.ts — core functions

// Burn (integer, min 0 — no cap)
function computeBurn(row, cfg) {
  const days = row.last_send_date
    ? daysBetween(cfg.todayDate, row.last_send_date)
    : 999; // no recency data → full decay pressure
  return Math.max(0,
    (row.sends_last_30  * cfg.sendWeight)
    - (row.clicks_last_30 * cfg.clickWeight)
    - (row.opens_last_30  * cfg.openWeight)
    - (days              * cfg.burnDecayRate)
  );
}

// Recovery (integer, min 0)
function computeRecovery(row, cfg, bands) {
  if (!row.last_gift_date) return 0;
  const spike = lookupSpikeHeight(row.last_gift_amount, bands);
  const days  = daysBetween(cfg.todayDate, row.last_gift_date);
  return Math.max(0, spike - (days * cfg.recoveryDecayRate));
}

// Velocity (0–100)
function computeVelocity(row) {
  if (row.lifetime_giving <= 0) return 0;
  return Math.round(
    Math.min(100, (row.this_year_giving / row.lifetime_giving) * 100)
  );
}

// Heat (0–100)
function computeHeat(row, cfg) {
  if (!row.first_gift_date || cfg.maxAnnualRate <= 0) return 0;
  const years = daysBetween(cfg.todayDate, row.first_gift_date) / 365.25;
  if (years <= 0) return 0;
  const annualRate = row.lifetime_giving / years;
  return Math.round(Math.min(100, (annualRate / cfg.maxAnnualRate) * 100));
}

// Quadrant
function assignQuadrant(velocity, heat, threshold) {
  const highV = velocity >= threshold;
  const highH = heat     >= threshold;
  if (highV && highH)  return 'Prime';
  if (highV && !highH) return 'Rising';
  if (!highV && highH) return 'Cooling';
  return               'Dormant';
}

Gift band lookup

const DEFAULT_GIFT_BANDS = [
  { minAmount: 10000, spikeHeight: 100 },
  { minAmount:  5000, spikeHeight:  80 },
  { minAmount:  1000, spikeHeight:  60 },
  { minAmount:   100, spikeHeight:  35 },
  { minAmount:     0, spikeHeight:  20 },
];

function lookupSpikeHeight(amount, bands) {
  for (const band of bands) {
    if (amount >= band.minAmount) return band.spikeHeight;
  }
  return 0;
}

Bands walk from highest to lowest. First match wins. Configure your own bands in the Config tab.