Function mergeData

src/install.ts:11–40

* Helper that recursively merges two data objects together.

(from: AnyObject, to: AnyObject)

 * Helper that recursively merges two data objects together.
 */
function mergeData(from: AnyObject, to: AnyObject): Object {
  if (!from) return to
  if (!to) return from

  let key: any
  let toVal: any
  let fromVal: any

  const keys = hasSymbol ? Reflect.ownKeys(from) : Object.keys(from)

  for (let i = 0; i < keys.length; i++) {
    key = keys[i]
    // in case the object is already observed...
    if (key === '__ob__') continue
    toVal = to[key]
    fromVal = from[key]
    if (!hasOwn(to, key)) {
      to[key] = fromVal
    } else if (
      toVal !== fromVal &&
      isPlainObject(toVal) &&
      !isRef(toVal) &&
      isPlainObject(fromVal) &&
      !isRef(fromVal)
    ) {
      mergeData(fromVal, toVal)
    }
  }
  return to
}

export function install(Vue: VueConstructor) {
  if (isVueRegistered(Vue)) {