Mizutsune

const phones = [
  { p: '9171857450', c: 1 },
  { p: '9880735438', c: 10 },
  { p: '9880735439', c: 100 },
  { p: '9880735779', c: 2 },
  { p: '9170997305', c: 2 },
  { p: '9170997493', c: 2 },
  { p: '9880634879', c: 5 },
  { p: '9170996154', c: 1 },
  { p: '9880728447', c: 1 },
];
const chancesTotal = phones.reduce((acc, { c }) => acc + c, 0);
const selected = Math.floor(Math.random() * chancesTotal);
let phone;
for (let i = 0, sum = 0; i < phones.length; i++) {
  sum += phones[i].c;
  if (selected < sum) {
    phone = phones[i].p;
    break;
  }
}
const randomUrl = `https://wa.me/${phone}?text=Привет!%20Пришлите%20мне%20цены%20на%20рыбку!`;

const makeDate = HHMM => {
  const [H, M] = HHMM.split(':').map(Number);
  const D = new Date();
  D.setHours(H);
  D.setMinutes(M);
  D.setSeconds(0);
  return D;
};

const oo = n => n.toString().padStart(2, '0'); // 5 => '05'

const fillTime = (startHHMM, finishHHMM, intervalMinutes) => {
  let startDate = makeDate(startHHMM);
  let finishDate = makeDate(finishHHMM);
  if (startDate > finishDate) { // объекты Date можно так сравнивать
    [startDate, finishDate] = [finishDate, startDate]; // поменять местами
  }

  const dates = [];
  const D = new Date(startDate);
  while (D <= finishDate) {
    dates.push(new Date(D));
    D.setMinutes(D.getMinutes() + intervalMinutes);
  }

  return dates.map(D => [D.getHours(), D.getMinutes()].map(oo).join(':'));
};

console.log(fillTime('15:56', '18:15', 17));
// [ "15:56", "16:13", "16:30", "16:47", "17:04", "17:21", "17:38", "17:55", "18:12" ]

const groupSum = (arr, idKey, ...sumKeys) =>
  Object.values(arr.reduce((acc, n) => (
    acc[n[idKey]] ??= sumKeys.reduce((group, k) => (group[k] = 0, group), { ...n }),
    sumKeys.forEach(k => acc[n[idKey]][k] += n[k]),
    acc
  ), {}));


const result = groupSum(arr, 'product', 'price', 'selling_price', 'quantity');

возвращает массив индексов элементов, у которые значение равно value.

const findIndex = (arr, value) => arr
  .map((v, i) => ({ v, i }))
  .filter(({ v }) => v === value)
  .map(({ i }) => i);

const textDecoder = new TextDecoder('windows-1251');
const response = await fetch(...);
const buffer = await response.arrayBuffer();
const text = textDecoder.decode(buffer);

(async function() {
    var result = await $.post('api/index.php', { raz: 'Привет, мир!' } );
    console.log('Ответ сервера:', result);
})();

<?php

header('Content-Type: text/plain; charset=UTF-8');

$json = json_encode($_POST, JSON_UNESCAPED_UNICODE);

file_put_contents('POST.json', $json);

echo 'Данные получены и записаны в файл POST.json -> смотри его.';

const clamp = (min, max, value) => Math.max(min, Math.min(max, value));

const calculateIntersection = (a, b) => {
    const aRect = a.getBoundingClientRect();
    const bRect = b.getBoundingClientRect();
    const top = clamp(aRect.top, aRect.bottom, bRect.top);
    const right = clamp(aRect.left, aRect.right, bRect.right);
    const bottom = clamp(aRect.top, aRect.bottom, bRect.bottom);
    const left = clamp(aRect.left, aRect.right, bRect.left);
    const width = right - left;
    const height = bottom - top;

    const totalArea = bRect.width * bRect.height;
    const intersectionArea = width * height;
    const intersectionRatio = intersectionArea / totalArea;

    return intersectionRatio;
};

<form action="receive_data.php" method="post">
  <input name="username">
  <button type="submit">Send</button>
</form>

<?php

$name = $_POST['username'];
$to      = 'nobody@example.com';
$subject = 'the subject';
$message = 'hello '.$name;
$headers = 'From: webmaster@example.com';
mail($to, $subject, $message, $headers);

header('Location: /other_page.php');

button {
  height: 64px;
  width: 256px;
  border-top-left-radius: 5px 50%;
  border-top-right-radius: 5px 50%;
  border-bottom-left-radius: 5px 50%;
  border-bottom-right-radius: 5px 50%;
  border: none;
}

function search(nums, target, searchMin) {
  for (let iMin = 0, iMax = nums.length - 1; iMin <= iMax; ) {
    const index = (iMin + iMax) / 2 | 0;
    const num = nums[index];

    if (num === target && num !== nums[index + (searchMin ? -1 : 1)]) {
      return index;
    } else if (num <= target - (searchMin ? 1 : 0)) {
      iMin = index + 1;
    } else {
      iMax = index - 1;
    }
  }

  return -1;
}

function searchMinMax(nums, target) {
  const iMin = search(nums, target, true);
  return iMin === -1
    ? []
    : [ iMin, search(nums, target, false) ];
}