如何优雅合并存在重叠键的多个JavaScript对象？

现有多个包含重叠键的对象，每个键代表一年中的某一周，对应的值是存储整数测试结果的对象，示例如下：

const ab_tests = { week1: { a: 4, b: 6 }, week2: { a: 0, b: 9 } };
const cd_tests = { week2: { c: 2, d: 5 }, week3: { c: 6, d: 7 } };
const xy_tests = { week1: { x: 1, y: 1 }, week4: { x: 100, y: 123 } };

需要将它们优雅地合并为一个单一对象，包含所有周作为键，对应值为合并后的对象，最终结果如下：

const merged_tests = {
  week1: { a: 4, b: 6, x: 1, y: 1 },
  week2: { a: 0, b: 9, c: 2, d: 5 },
  week3: { c: 6, d: 7 },
  week4: { x: 100, y: 123 },
};

方法一：原生JS结合reduce与展开语法 #

把所有待合并对象放进数组，通过reduce遍历累积结果，对每个周的对象用展开语法合并属性，逻辑清晰且无依赖：

const testObjects = [ab_tests, cd_tests, xy_tests];

const merged_tests = testObjects.reduce((acc, curr) => {
  for (const week in curr) {
    acc[week] = { ...(acc[week] || {}), ...curr[week] };
  }
  return acc;
}, {});

方法二：原生JS结合reduce与Object.assign #

和上一种思路一致，用Object.assign替代展开语法完成属性合并：

const testObjects = [ab_tests, cd_tests, xy_tests];

const merged_tests = testObjects.reduce((acc, curr) => {
  for (const week in curr) {
    acc[week] = Object.assign({}, acc[week] || {}, curr[week]);
  }
  return acc;
}, {});

方法三：Lodash的merge函数（项目已引入Lodash时使用） #

如果项目依赖Lodash，一行代码即可完成递归合并，简洁高效：

const merged_tests = _.merge({}, ab_tests, cd_tests, xy_tests);

内容的提问来源于stack exchange，提问作者benito_h