fs.exists, fs.existsSync - why are they deprecated?

Question

I noticed that the official node documentation says something startling about fs.exists:

"fs.exists() is an anachronism and exists only for historical reasons. There should almost never be a reason to use it in your own code.

In particular, checking if a file exists before opening it is an anti-pattern that leaves you vulnerable to race conditions: another process may remove the file between the calls to fs.exists() and fs.open(). Just open the file and handle the error when it's not there."

I understand the suggestion, to open a file and then handle the error if it doesn't exist, but what I don't understand is why the interface is being deprecated rather than the implementation simply changing.

Can anyone explain to me why checking for the existence of a file with an API that is as simple and logical as fs.exists is such a bad thing that it should be called an anti-pattern and removed from the node API?

Answer 1

There is no need to use fs.stat(), because fs.existsSync() has not been deprecated.

https://nodejs.org/api/fs.html#fs_fs_existssync_path

fs.existsSync(path)

Added in: v0.1.21 path | Synchronous version of fs.exists(). Returns true if the file exists, false otherwise.

Note that fs.exists() is deprecated, but fs.existsSync() is not. (The callback >parameter to fs.exists() accepts parameters that are inconsistent with other >Node.js callbacks. fs.existsSync() does not use a callback.)