export function getCacheKey ( request ) { const pragma = request . headers . get ( "pragma" ) ; if ( pragma === "no-cache" ) { return null ; } const cacheControl = request . headers . get ( "cache-control" ) ; if ( cacheControl ) { const directives = new Set ( cacheControl . split ( "," ) . map ( ( s ) => s . trim ( ) ) ) ; if ( directives . has ( "no-store" ) || directives . has ( "no-cache" ) ) { return null ; } } return request . url ; }