An upgrade of zlib from 1.2.8 to 1.2.11 changed behavior when windowBits is set to 8 for raw deflate streams. zlib would automatically set windowBits to 9 if was initially set to 8. Newer
versions of zlib will throw an exception,
so Node.js restored the original behavior of upgrading a value of 8 to 9,
since passing windowBits = 9 to zlib actually results in a compressed stream
that effectively uses an 8-bit window only.
Creates and returns a new
DeflateRawobject.An upgrade of zlib from 1.2.8 to 1.2.11 changed behavior when
windowBitsis set to 8 for raw deflate streams. zlib would automatically setwindowBitsto 9 if was initially set to 8. Newer versions of zlib will throw an exception, so Node.js restored the original behavior of upgrading a value of 8 to 9, since passingwindowBits = 9to zlib actually results in a compressed stream that effectively uses an 8-bit window only.