如何合并多组错误对象数组为单个对象并简化现有实现？

需求：将包含100余种不同键名的无类型对象数组，把所有类型对应的错误对象合并为一个单一对象。

输入示例 #

const input = [
    {
        "type":"cat",
        "errors":[
            {
                "keyA":"This is wrong!",
                "keyB":"This is more wrong!!",
                "keyC":"...horrible, just horrible"
            }
        ]
    },
    {
        "type":"dog",
        "errors":[
            {
                "key1":"whoops",
                "key2":"somebody has a typo"
            },
            {
                "keyX":"umm...really?",
                "keyY":"when did it start raining?"
            }
        ]
    }
]

期望输出 #

{
    "keyA":"This is wrong!",
    "keyB":"This is more wrong!!",
    "keyC":"...horrible, just horrible",
    "key1":"whoops",
    "key2":"somebody has a typo",
    "keyX":"umm...really?",
    "keyY":"when did it start raining?"
}

当前实现（可运行但希望更简洁） #

const returnVal = val.reduce((acc,curr) => {
    return ([...acc.errors, ...curr.errors] as any).reduce((a: any, c: any) => ({...a, ...c}), {});
});

更简洁的实现方案 #

方案1：flatMap + Object.assign合并 #

用flatMap直接提取所有嵌套的错误对象，再通过Object.assign一次性合并到空对象中，完全避免嵌套调用：

const mergedErrors = Object.assign({}, ...input.flatMap(item => item.errors));

方案2：单次reduce完成合并 #

如果不想用flatMap，可以用单次reduce遍历数组，每次将当前项的错误对象合并到累计结果中：

const mergedErrors = input.reduce((acc, item) => {
  return {...acc, ...Object.assign({}, ...item.errors)};
}, {});

方案3：Object.fromEntries展开键值对 #

把所有错误对象的键值对展开为二维数组，再通过Object.fromEntries转换为目标对象：

const mergedErrors = Object.fromEntries(
  input.flatMap(item => item.errors.flatMap(err => Object.entries(err)))
);

注：以上方案均和原实现逻辑一致——若存在重复键名，后出现的键值会覆盖之前的。

内容的提问来源于stack exchange，提问作者Wonder Twin