pre rendering에 사용되는 메서드들은 모두 context 인자를 받는다.

• params: If this page uses a dynamic route, params contains the route parameters. If the page name is [id].js , then params will look like { id: ... }. 동적 라우팅에 사용되는 페이지만 가능하다.
• req: The HTTP IncomingMessage object.
• res: The HTTP response object.
• query: An object representing the query string.
• preview: preview is true if the page is in the Preview Mode and false otherwise.
• previewData: The preview data set by setPreviewData.
• resolvedUrl: A normalized version of the request URL that strips the _next/data prefix for client transitions and includes original query values.
• locale contains the active locale (if enabled).
• locales contains all supported locales (if enabled).
• defaultLocale contains the configured default locale (if enabled).