The file's attributes. These are traditionally somewhat complicated and platform-dependent, so using them is scarcely necessary. However, here is a representation of what this is, bit by bit:
TTTTugtrwxrwxrwx0000000000ADVSHR
TTTT = file type (rarely useful)
u = setuid, g = setgid, t = sticky
rwx = user permissions, rwx = group permissions, rwx = other permissions
0000000000 = unused
A = archive, D = directory, V = volume label, S = system file, H = hidden, R = read-only
If you want to set the Unix permissions, for instance, just bit shift by 16, e.g. 0644 << 16
The comment to attach to the file. This field is defined by PKZIP's APPNOTE.txt, section 4.4.26. The comment must be at most 65,535 bytes long UTF-8 encoded. This field is not read by consumer software.
Whether or not to "consume" the source data. This will make the typed array/buffer you pass in unusable but will increase performance and reduce memory usage.
Extra metadata to add to the file. This field is defined by PKZIP's APPNOTE.txt, section 4.4.28. At most 65,535 bytes may be used in each ID. The ID must be an integer between 0 and 65,535, inclusive.
This field is incredibly rare and almost never needed except for compliance with proprietary standards and software.
The level of compression to use, ranging from 0-9.
0 will store the data without compression. 1 is fastest but compresses the worst, 9 is slowest but compresses the best. The default level is 6.
Typically, binary data benefits much more from higher values than text data. In both cases, higher values usually take disproportionately longer than the reduction in final size that results.
For example, a 1 MB text file could:
The memory level to use, ranging from 0-12. Increasing this increases speed and compression ratio at the cost of memory.
Note that this is exponential: while level 0 uses 4 kB, level 4 uses 64 kB, level 8 uses 1 MB, and level 12 uses 16 MB. It is recommended not to lower the value below 4, since that tends to hurt performance. In addition, values above 8 tend to help very little on most data and can even hurt performance.
The default value is automatically determined based on the size of the input data.
When the file was last modified. Defaults to the current time.
The operating system of origin for this file. The value is defined by PKZIP's APPNOTE.txt, section 4.4.2.2. For example, 0 (the default) is MS/DOS, 3 is UNIX, 19 is macOS.
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Options for asynchronously creating a ZIP archive