दिन 4: Loops: for, while, for…of

// for (start; keep going while…; after each round)
for (let i = 1; i <= 5; i++) {
  console.log(`9 × ${i} = ${9 * i}`);
}

const prices = [900, 650, 700, 500];
let total = 0;
for (const price of prices) {
  total += price;
}
console.log('Total of one kg each:', total);
console.log('Average price:', total / prices.length);

for (const letter of 'Ghewar') {
  process.stdout.write(letter + ' ');
}
console.log();

// How many months to save ₹20,000 if you save ₹1,500 a month and get ₹200 bonus every 4th month?
let saved = 0, month = 0;
while (saved < 20000) {
  month++;
  saved += 1500;
  if (month % 4 === 0) saved += 200;
}
console.log(`Goal reached in ${month} months with ₹${saved}`);

let tries = 0;
do {
  tries++;
  console.log('Attempt', tries);
} while (tries < 1);   // runs once even though the condition is false afterwards

const orders = [450, 0, 1200, -50, 3000, 800];
for (const amount of orders) {
  if (amount <= 0) {
    console.log('skip invalid', amount);
    continue;               // jump to the next item
  }
  if (amount > 2500) {
    console.log('big order found:', amount, '→ call the manager, stop checking');
    break;                  // leave the loop completely
  }
  console.log('ok', amount);
}

const stock = { kaju: 25, ghewar: 8, rasmalai: 0 };
for (const item in stock) {
  console.log(item, stock[item] > 0 ? 'available' : 'SOLD OUT');
}

for (let row = 1; row <= 4; row++) {
  let line = '';
  for (let col = 1; col <= row; col++) {
    line += '🍬';
  }
  console.log(line);
}

// attendance: 3 students × 5 days
const attendance = [
  ['Aarav', 'P', 'P', 'A', 'P', 'P'],
  ['Riya',  'P', 'P', 'P', 'P', 'P'],
  ['Kabir', 'A', 'P', 'A', 'P', 'A'],
];
for (const [name, ...days] of attendance) {
  let present = 0;
  for (const d of days) if (d === 'P') present++;
  console.log(`${name.padEnd(6)} ${present}/5  ${present >= 4 ? '✅' : '⚠️ low'}`);
}

<label>Table of <input id="n" type="number" value="13" style="width:70px"></label>
<button id="show">Show</button>
<ol id="list"></ol>

<script>
document.querySelector('#show').addEventListener('click', function () {
  const n = Number(document.querySelector('#n').value);
  let html = '';
  for (let i = 1; i <= 10; i++) {
    html += `<li>${n} × ${i} = <b>${n * i}</b></li>`;
  }
  document.querySelector('#list').innerHTML = html;
});
</script>