简易 _.set & _.get

setter.js

const setter = (obj, key, value) => {
  const keys = key.split(".");
  const pres = keys.slice(0, -1);
  const last = keys[keys.length - 1];
  const deepObj =
    keys.length === 1
      ? obj
      : pres.reduce((curObj, curKey) => {
          // eslint-disable-next-line no-param-reassign
          if (!curObj[curKey]) curObj[curKey] = {};
          return curObj[curKey];
        }, obj);
  deepObj[last] = value;
  return obj;
};

const getter = (obj, key) => {
  const keys = key.split(".");
  const value = keys.reduce((curObj, curKey) => curObj[curKey], obj);
  return value;
};

const obj = {};

setter(obj, "person.name", "jc");
setter(obj, "person.age", 18);

// { person: { name: 'jc', age: 18 } }
console.log(obj);

const age = getter(obj, "person.age");

// 18
console.log(age);