使用javascript将数组中的多个对象合并为一个基于键值对的对象

function mergeObjects(arr) {
  var result = {};
  
  arr.forEach(function(obj) {
    for (var 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;
}

var arr = [
  { name: 'John', age: 25 },
  { name: 'Jane', gender: 'female' },
  { name: 'Bob', age: 30, gender: 'male' }
];

var mergedObj = mergeObjects(arr);
console.log(mergedObj);

{
  name: ['John', 'Jane', 'Bob'],
  age: [25, 30],
  gender: ['female', 'male']
}