vue-cli/packages/@vue/cli-shared-utils/lib/object.js

exports.set = function (target, path, value) {
  const fields = path.split('.')
  let obj = target
  const l = fields.length
  for (let i = 0; i < l - 1; i++) {
    const key = fields[i]
    if (!obj[key]) {
      obj[key] = {}
    }
    obj = obj[key]
  }
  obj[fields[l - 1]] = value
}

exports.get = function (target, path) {
  const fields = path.split('.')
  let obj = target
  const l = fields.length
  for (let i = 0; i < l - 1; i++) {
    const key = fields[i]
    if (!obj[key]) {
      return undefined
    }
    obj = obj[key]
  }
  return obj[fields[l - 1]]
}

exports.unset = function (target, path) {
  const fields = path.split('.')
  let obj = target
  const l = fields.length
  const objs = []
  for (let i = 0; i < l - 1; i++) {
    const key = fields[i]
    if (!obj[key]) {
      return
    }
    objs.unshift({ parent: obj, key, value: obj[key] })
    obj = obj[key]
  }
  delete obj[fields[l - 1]]
  // Clear empty objects
  for (const { parent, key, value } of objs) {
    if (!Object.keys(value).length) {
      delete parent[key]
    }
  }
}