如何在指定位置添加/修改对象键值对（适配YAML转换需求）

因为后续要将对象转换为YAML格式，对象键的顺序至关重要，需要保证version键始终处于第二位。存在三种场景：

目标状态示例 #

{
    "$schema": "../../../project-schema.json",
    "version": "1.2.3", // 需要将version添加或移动到此处，并修改值
    "sourceRoot": "apps/backend/src",
    "projectType": "application"
}

场景1：version键完全缺失 #

{
    "$schema": "../../../project-schema.json",
    "sourceRoot": "apps/backend/src",
    "projectType": "application"
}

场景2：version键位置错误 #

{
    "$schema": "../../../project-schema.json",
    "sourceRoot": "apps/backend/src",
    "projectType": "application",
    "version": "1.2.3"
}

现有问题 #

我尝试用reduce函数处理，但该方法仅在version完全缺失时有效：

const insertKey = (key, value, obj, pos) => {
  return Object.keys(obj).reduce((ac, a, i) => {    
    if (i === pos) ac[key] = value
    ac[a] = obj[a]
    return ac
  }, {})
}

insertKey('version', '2.3.4', obj, 1)

解决方案 #

可以通过以下函数处理所有场景，确保目标键被插入/移动到指定位置并更新值：

const insertOrMoveKey = (targetKey, targetValue, obj, targetPos) => {
  // 移除原对象中的目标键（避免重复）
  const { [targetKey]: _, ...restObj } = obj;
  const restKeys = Object.keys(restObj);
  // 在指定位置插入目标键，生成新的键顺序数组
  const newKeyOrder = [...restKeys.slice(0, targetPos), targetKey, ...restKeys.slice(targetPos)];
  // 按新顺序构建对象
  return newKeyOrder.reduce((result, key) => {
    result[key] = key === targetKey ? targetValue : restObj[key];
    return result;
  }, {});
};

测试示例 #

处理version缺失的对象

const objWithoutVersion = {
    "$schema": "../../../project-schema.json",
    "sourceRoot": "apps/backend/src",
    "projectType": "application"
};
console.log(insertOrMoveKey('version', '2.3.4', objWithoutVersion, 1));

输出：

{
    "$schema": "../../../project-schema.json",
    "version": "2.3.4",
    "sourceRoot": "apps/backend/src",
    "projectType": "application"
}

处理version位置错误的对象

const objWithWrongVersionPos = {
    "$schema": "../../../project-schema.json",
    "sourceRoot": "apps/backend/src",
    "projectType": "application",
    "version": "1.2.3"
};
console.log(insertOrMoveKey('version', '2.3.4', objWithWrongVersionPos, 1));

输出：

{
    "$schema": "../../../project-schema.json",
    "version": "2.3.4",
    "sourceRoot": "apps/backend/src",
    "projectType": "application"
}

处理version位置正确的对象

const objWithCorrectVersionPos = {
    "$schema": "../../../project-schema.json",
    "version": "1.2.3",
    "sourceRoot": "apps/backend/src",
    "projectType": "application"
};
console.log(insertOrMoveKey('version', '2.3.4', objWithCorrectVersionPos, 1));

输出：

{
    "$schema": "../../../project-schema.json",
    "version": "2.3.4",
    "sourceRoot": "apps/backend/src",
    "projectType": "application"
}

逻辑说明 #

1. 先通过解构赋值移除原对象中的目标键，避免重复添加
2. 基于剩余键的数组，在指定位置插入目标键，生成新的键顺序
3. 遍历新的键顺序数组构建对象，目标键使用传入的新值，其余键保留原对象的值

内容的提问来源于stack exchange，提问作者user3142695