some and every In Manipulate JavaScript Array

const add = (...entries) => {
  return entries.filter(Number.isInteger).reduce((sum, int) => {
    return sum + int;
  }, 0);
};

const add = (...entries) => {
  return entries.reduce((sum, entry) => {
    if (Number.isInteger(entry)) {
      return sum + entry;
    }
    return sum;
  }, 0);
};

const add = (...entries) => {
  let theSum = 0;
  if (hasTwoOrMoreInts(entries)) {
    // there are >= 2 integers, lets sum them
    theSum = entries.reduce((sum, entry) => {
      if (Number.isInteger(entry)) {
        return sum + entry;
      }
      return sum;
    }, 0);
  }
  return theSum;
};
 
const hasTwoOrMoreInts = entries => {
  let lastIndex = -1;
  let hasMinimumIntsCount = false;
 
  const hasAnInt = entries.some((entry, index) => {
    lastIndex = index;
    return Number.isInteger(entry);
  });
 
  if (hasAnInt === true) {
    // we've got one int, is there another?
    const hasMoreInts = entries.slice(lastIndex + 1).some(Number.isInteger);
    hasMinimumIntsCount = hasMoreInts === true && hasAnInt;
  }
 
  return hasMinimumIntsCount;
};

const add = (...entries) => {
  let theSum = 0;
  const areAllInts = entries.every(Number.isInteger);
  if (areAllInts === true) {
    // are these indeed all ints?
    theSum = entries.reduce((sum, int) => {
      return sum + int;
    }, 0);
  }
  return theSum;
};