在合并对象的键中创建值数组

function mergeObjects(...objects) {
  return objects.reduce((result, obj) => {
    for (let key in obj) {
      if (result.hasOwnProperty(key)) {
        if (Array.isArray(result[key])) {
          result[key].push(obj[key]);
        } else {
          result[key] = [result[key], obj[key]];
        }
      } else {
        result[key] = obj[key];
      }
    }
    return result;
  }, {});
}

const obj1 = { a: 1, b: 2 };
const obj2 = { a: 3, c: 4 };
const mergedObj = mergeObjects(obj1, obj2);

console.log(mergedObj);
// Output: { a: [1, 3], b: 2, c: 4 }