# Caver-js-ext-kas TypeError: os.type is not a function

**URL:** <https://devforum.kaia.io/t/caver-js-ext-kas-typeerror-os-type-is-not-a-function/5396>\
**Category:** KAS (아카이브)\
**Tags:** caver-js\
**Created:** [6월 7, 2022, 3:16오전 UTC](https://devforum.kaia.io/t/caver-js-ext-kas-typeerror-os-type-is-not-a-function/5396 "2022-06-07T03:16:52Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Dgn](https://avatars.discourse-cdn.com/v4/letter/d/7ab992/32.png) [@Dgn](https://devforum.kaia.io/u/Dgn)\
**Post date:** [6월 7, 2022, 3:16오전 UTC](https://devforum.kaia.io/t/caver-js-ext-kas-typeerror-os-type-is-not-a-function/5396/1 "2022-06-07T03:16:52Z")

</div>

현재 next.js 에서 개발 중 TypeError: os.type is not a function 이런 에러가 뜨는데 webpack을 수정해도 동일한 에러가 계속 나옵니다. caver-js는 작동하는데 혹시 KASCypress로 배포한 컨트렉트 호출을 caver-js로 해도 문제 없을까요?

---

<div class="post-metadata">

**Author:** ![jack\_jin](https://yyz1.discourse-cdn.com/flex035/user_avatar/devforum.kaia.io/jack_jin/32/2305_2.png) [@jack\_jin](https://devforum.kaia.io/u/jack_jin)\
**Post date:** [6월 7, 2022, 3:32오전 UTC](https://devforum.kaia.io/t/caver-js-ext-kas-typeerror-os-type-is-not-a-function/5396/2 "2022-06-07T03:32:42Z")

</div>

안녕하세요, 질문을 조금만 구체적으로 해주시면 좋을것같습니다. `os.type`에러가 나서 contract호출을 고려하고 계시다는 말씀이신 건가요?