Inserting a value into an object with a path string and the second file is about finding a value in an object with a path

insertIntoObjectByPath.js

function createObjectFromPath (root, path, value) {
  const segments = path.split('.')
  let cursor = root
  let segment
  for (let i = 0; i < segments.length; i++) {
    segment = segments[i]
    if (segment === '[]') {
      continue
    }
    let newObj = cursor[segment] || {}
    if (i + 1 < segments.length && segments[i + 1] === '[]') {
      if (!cursor[segment] || !Array.isArray(cursor[segment])) {
        newObj = [{}]
        cursor = cursor[segment] = newObj
        cursor = newObj[0]
      } else {
        newObj = {}
        cursor[segment].push(newObj)
        cursor = newObj
      }
    }
    else {
      if (i === segments.length - 1) {
        cursor = cursor[segment] = value
      } else {
        cursor = cursor[segment] = newObj
      }
    }

  }
}

const r = {}
createObjectFromPath(r, 'a.[].b.c', 5)
console.log(r)
createObjectFromPath(r, 'a.[].b.c', 6)
console.log(r)
createObjectFromPath(r, 'a.[].b.d', 7)
console.log(r)

readFromObjectByPath.js

function findFieldsByPath (subjectObject, path, successCallback = undefined) {
  let current = subjectObject
  const fields = path.split('.')
  if (fields.includes('')) {
    console.error(`[findFieldsByPath] Invalid path ${path}`)
  }
  const result = {
    path: path,
    parents: [],
    fieldValues: [],
    fieldName: '',
    isSuccess: false
  }
  for (let i = 0; i < fields.length; i++) {
    const subField = fields[i]
    if (i === fields.length - 1 && current !== undefined) {
      result.parents = [current]
      result.fieldValues = [current[subField]]
      result.fieldName = subField
      result.isSuccess = true
      break
    } else {
      if (current && typeof current !== 'string') {
        if (subField in current) {
          current = current[subField]
        } else if (subField === '[]' && Array.isArray(current)) {
          const addSubResults = ({ parents, fieldName, fieldValues }) => {
            result.parents = result.parents.concat(parents)
            result.fieldName = fieldName
            result.fieldValues = result.fieldValues.concat(fieldValues)
            result.isSuccess = true
          }
          for (let k = 0; k < current.length; k++) {
            findFieldsByPath(current[k], fields.slice(i + 1).join('.'), addSubResults)
          }
          break
        }
      } else {
        current = undefined
      }
    }
  }
  if (result.isSuccess) {
    if (typeof successCallback === 'function') {
      successCallback(result)
    } else {
      return result
    }
  }
}

subject = {
  a: {
    b: {
      people: [{ name: 'Amin', last: 'Soltani' }, { name: 'Darya', last: 'who?' }]
    }
  },
  c: {
    name: 'WRONG'
  }
}

path = 'a.b.people.[].name'

console.log(findFieldsByPath(subject, path))