===== ISTEM =====
Solve the following programming task.

TASK: Object Diff

Write a function 'objectDiff(obj1, obj2)' that compares two JavaScript objects and returns only the changed properties as [oldValue, newValue].

STARTER CODE (javascript):
function objectDiff(obj1, obj2) {
  // Write your code here
}

module.exports = { objectDiff };


RULES:
- Keep the function name and signature EXACTLY as given.
- Return working code only. No explanations.
- Put the code in a single ``` block.
- Try to solve it first. If you genuinely cannot, write only this single
  line instead of producing faulty code: CANNOT_SOLVE

===== HAM YANIT =====
```javascript
const { isDeepStrictEqual } = require('util');

function objectDiff(obj1, obj2) {
  const diff = {};
  const keys = new Set([...Object.keys(obj1), ...Object.keys(obj2)]);
  const hasOwn = (obj, key) =>
    Object.prototype.hasOwnProperty.call(obj, key);

  for (const key of keys) {
    const inFirst = hasOwn(obj1, key);
    const inSecond = hasOwn(obj2, key);
    const oldValue = inFirst ? obj1[key] : undefined;
    const newValue = inSecond ? obj2[key] : undefined;

    if (inFirst !== inSecond || !isDeepStrictEqual(oldValue, newValue)) {
      Object.defineProperty(diff, key, {
        value: [oldValue, newValue],
        enumerable: true,
        writable: true,
        configurable: true
      });
    }
  }

  return diff;
}

module.exports = { objectDiff };
```