Return to Answer

const get = (t, path) =>
  path.split(".").reduce((r, k) => r?.[k], t)

const set = (t, path, value) => {
  if (path == "") return value
  const [k, next] = path.split({
    [Symbol.split](s) {
      const i = s.indexOf(".")
      return i == -1 ? [s, ""] : [s.slice(0, i), s.slice(i + 1)]
    }
  })
  if (t !== undefined && typeof t !== "object")
    throw Error(`cannot set property ${k} of ${typeof t}`)
  return Object.assign(
    t ?? (/^\d+$/.test(k) ? [] : {}),
    { [k]: set(t?.[k], next, value) },
  )
}

// build data from previous example
const mydata = set({}, "a.b", [
  0,
  set({}, "c.d", ["hello", "world"])
])

// print checkpoint
console.log(JSON.stringify(mydata, null, 2))

// set additional fields
set(mydata, "a.b.1.c.d.1", "moon")
set(mydata, "a.b.1.w", "x.y.z")

// ensure changes
console.log(JSON.stringify(mydata, null, 2))

.as-console-wrapper { min-height: 100%; top: 0; }

const get = (t, path) =>
  path.split(".").reduce((r, k) => r?.[k], t)

const set = (t, path, value) => {
  if (path == "") return value
  const [k, next] = path.split({
    [Symbol.split](s) {
      const i = s.indexOf(".")
      return i == -1 ? [s, ""] : [s.slice(0, i), s.slice(i + 1)]
    }
  })
  if (t !== undefined && typeof t !== "object")
    throw Error(`cannot set property ${k} of ${typeof t}`)
  return Object.assign(
    t ?? (/^\d+$/.test(k) ? [] : {}),
    { [k]: set(t?.[k], next, value) },
  )
}

// build data from previous example
const mydata = set({}, "a.b.0.c.d", ["hello", "world"])

// print checkpoint
console.log(JSON.stringify(mydata, null, 2))

// set additional fields
set(mydata, "a.b.1.c.d.1", "moon")
set(mydata, "a.b.1.w", "x.y.z")

// ensure changes
console.log(JSON.stringify(mydata, null, 2))

.as-console-wrapper { min-height: 100%; top: 0; }

const get = (t, path) =>
  path.split(".").reduce((r, k) => r?.[k], t)

const set = (t, path, value) => {
  if (path == "") return value
  const [k, ...next] = path.split(".")
  if (t !== undefined && typeof t !== "object")
    throw Error(`cannot set property ${k} of ${typeof t}`)
  return Object.assign(
    t ?? (/^\d+$/.test(k) ? [] : {}),
    { [k]: set(t?.[k], next.join("."), value) },
  )
}

// build data from previous example
const mydata = set({}, "a.b", [
  0,
  set({}, "c.d", ["hello", "world"])
])

// print checkpoint
console.log(JSON.stringify(mydata, null, 2))

// set additional fields
set(mydata, "a.b.1.c.d.1", "moon")
set(mydata, "a.b.1.w", "x.y.z")

// ensure changes
console.log(JSON.stringify(mydata, null, 2))

.as-console-wrapper { min-height: 100%; top: 0; }

const get = (t, path) =>
  path.split(".").reduce((r, k) => r?.[k], t)

const set = (t, path, value) => {
  if (path == "") return value
  const [k, next] = path.split({
    [Symbol.split](s) {
      const i = s.indexOf(".")
      return i == -1 ? [s, ""] : [s.slice(0, i), s.slice(i + 1)]
    }
  })
  if (t !== undefined && typeof t !== "object")
    throw Error(`cannot set property ${k} of ${typeof t}`)
  return Object.assign(
    t ?? (/^\d+$/.test(k) ? [] : {}),
    { [k]: set(t?.[k], next, value) },
  )
}

// build data from previous example
const mydata = set({}, "a.b", [
  0,
  set({}, "c.d", ["hello", "world"])
])

// print checkpoint
console.log(JSON.stringify(mydata, null, 2))

// set additional fields
set(mydata, "a.b.1.c.d.1", "moon")
set(mydata, "a.b.1.w", "x.y.z")

// ensure changes
console.log(JSON.stringify(mydata, null, 2))

.as-console-wrapper { min-height: 100%; top: 0; }