Find the missing numbers in a range

missingNumbers.js

export default function missingNumbers(numbers) {
  const numSet = new Set(numbers);
  let max = Math.max(...numbers);
  let min = Math.min(...numbers);
  return Array.from({ length: max - min }, (_, i) => i + min).filter(
    (num) => num > 0 && !numSet.has(num),
  );
}

missingNumbers.spec.js

import missingNumbers from "./missingNumbers.js";

function test_missing_numbers() {
  function arraysEqual(a, b) {
    if (a.length !== b.length) return false;
    for (let i = 0; i < a.length; i++) {
      if (a[i] !== b[i]) return false;
    }
    return true;
  }

  // Test cases
  const testCases = [
    { input: [9, 6, 10, 5], expected: [7, 8] },
    { input: [22, 23, 20, 15], expected: [16, 17, 18, 19, 21] },
    { input: [9, 6, 10, 5, -1], expected: [7, 8] },
    { input: [1, 2.5, 4.25, 2.75], expected: [3, 4] },
  ];

  testCases.forEach(({ input, expected }, index) => {
    const result = missingNumbers(input);
    if (arraysEqual(result, expected)) {
      console.log(`Test case ${index + 1} passed.`);
    } else {
      console.log(`Test case ${index + 1} failed. Expected ${expected}, but got ${result}.`);
    }
  });
}

test_missing_numbers();

package.json

{
  "type": "module"
}