Day 9: Strings, Numbers, Money & Dates

const raw = '  aarti GUPTA ';
const clean = raw.trim().toLowerCase().split(' ').filter(Boolean)
  .map(w => w[0].toUpperCase() + w.slice(1)).join(' ');
console.log(`"${clean}"`);

const phone = '+91 98290-12345';
const digits = phone.replace(/\D/g, '').slice(-10);     // keep the last 10 digits
console.log(digits, digits.length === 10);

const masked = digits.slice(0, 2) + '******' + digits.slice(-2);
console.log('OTP sent to', masked);

const invoiceNo = String(42).padStart(5, '0');
console.log(`INV-${invoiceNo}`);
console.log('Kaju Katli'.includes('Katli'), 'ghewar'.startsWith('ghe'), 'menu.pdf'.endsWith('.pdf'));
console.log('a-b-c'.replaceAll('-', ' / '), 'Ladoo'.at(-1), 'Rasmalai'.length);

console.log(Math.round(4.5), Math.floor(4.9), Math.ceil(4.1), Math.trunc(-4.7));
console.log(Math.max(380, 900, 650), Math.min(...[380, 900, 650]));
console.log(Math.abs(-250), Math.sqrt(144), Math.PI.toFixed(4));

const r = Math.round(1234.567 * 100) / 100;   // round to 2 decimals as a NUMBER
console.log(r, (1234.567).toFixed(2), typeof (1234.567).toFixed(2));   // toFixed returns a STRING

const otp = Math.floor(100000 + Math.random() * 900000);   // 6-digit OTP (demo only!)
console.log(String(otp).length);
console.log(Number.isInteger(5.0), Number.isFinite(1 / 0), Number.MAX_SAFE_INTEGER);

console.log(0.1 + 0.2);                       // 0.30000000000000004 ❌
console.log(0.1 + 0.2 === 0.3);

// ✅ Store money as integer paise, convert only for display
const itemsPaise = [45050, 32075, 9990];      // ₹450.50, ₹320.75, ₹99.90
const subtotal = itemsPaise.reduce((s, p) => s + p, 0);
const gst = Math.round(subtotal * 5 / 100);   // round once, at the end
const total = subtotal + gst;
console.log(subtotal, gst, total);
console.log('Pay ₹' + (total / 100).toFixed(2));

const inr = new Intl.NumberFormat('en-IN', { style: 'currency', currency: 'INR' });
console.log(inr.format(1234567.5));
console.log(new Intl.NumberFormat('en-IN', { style: 'currency', currency: 'INR', maximumFractionDigits: 0 }).format(48200));
console.log(new Intl.NumberFormat('hi-IN', { style: 'currency', currency: 'INR' }).format(9999));
console.log(new Intl.NumberFormat('en-IN', { notation: 'compact' }).format(2500000));
console.log((1234567).toLocaleString('en-IN'));
console.log(new Intl.NumberFormat('en-IN', { style: 'percent', maximumFractionDigits: 1 }).format(0.1234));

const order = new Date('2026-10-25T10:30:00+05:30');   // ISO format = safe to parse
const delivery = new Date(order);
delivery.setDate(delivery.getDate() + 3);                // add 3 days

const fmt = new Intl.DateTimeFormat('en-IN', { weekday: 'short', day: 'numeric', month: 'short', year: 'numeric', timeZone: 'Asia/Kolkata' });
console.log('Ordered:', fmt.format(order));
console.log('Delivery by:', fmt.format(delivery));
console.log(new Intl.DateTimeFormat('hi-IN', { dateStyle: 'full', timeZone: 'Asia/Kolkata' }).format(delivery));

const diwali = new Date('2026-11-08T00:00:00+05:30');
const daysLeft = Math.ceil((diwali - order) / (1000 * 60 * 60 * 24));
console.log(`${daysLeft} days to Diwali 🪔`);

function age(dobIso, onIso) {
  const dob = new Date(dobIso), on = new Date(onIso);
  let years = on.getFullYear() - dob.getFullYear();
  const birthdayPassed = on.getMonth() > dob.getMonth() || (on.getMonth() === dob.getMonth() && on.getDate() >= dob.getDate());
  return birthdayPassed ? years : years - 1;
}
console.log('Age:', age('2008-12-15', '2026-10-25'));

<p style="font-size:1.3rem">🪔 Diwali sale ends in <b id="left"></b></p>

<script>
const end = new Date();
end.setDate(end.getDate() + 2);          // demo: always 2 days from now
end.setHours(23, 59, 59, 0);

function tick() {
  let ms = Math.max(0, end - new Date());
  const d = Math.floor(ms / 86400000); ms %= 86400000;
  const h = Math.floor(ms / 3600000); ms %= 3600000;
  const m = Math.floor(ms / 60000);
  const s = Math.floor((ms % 60000) / 1000);
  const two = n => String(n).padStart(2, '0');
  document.querySelector('#left').textContent = `${d}d ${two(h)}h ${two(m)}m ${two(s)}s`;
}
tick();
setInterval(tick, 1000);
</script>