What does it mean that "file is truncated" for the 'w' file system flag?

Question

In the documentation for the Node.js fs module, under "File System flags", it says:

'w' - Open file for writing. The file is created (if it does not exist) or truncated (if it exists).

Truncated to what size? 0 bytes?

Answer 1

Yes, the 'w' flag will truncate the file to 0 bytes before writing -- effectively overwriting the file if it exists. (As opposed to the 'a' flag, which will append to the end of an existing file.)