Access to fetch at ''url" from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled. ❓상황 fetch를 이용하여 한국환경공단_에어코리아_대기오염정보 API 호출시 발생한 오류 🔎 원인 파악 외부 API 접근시, 브라우저가 클라이언트의 Origin값과 외부 API 서버의 Ac..