Buffer with callback doesn't work

[phawxby]

The codepath for input strings allows for the callback to be invoked.
https://github.com/image-size/image-size/blob/master/lib/index.js#L118

But the codepath for buffers does not, it's always a return breaking the promise.
https://github.com/image-size/image-size/blob/master/lib/index.js#L96

[netroy]

@phawxby operating on a buffer, in this case, isn't an async operation.
Can you please share more info on how this is being used in an async way?

[phawxby]

const got = require('got');
const { promisify } = require('util');
const sizeOf = promisify(require('image-size'));

const resp = await got('https://www.foo.com/foo.png', { encoding: null });
const dimensions = await sizeOf(resp.body); // resp.body is a buffer when the encoding is null

I've fixed it for now by not promisifying sizeOf but it is breaking the terms of the callback/promise if there is a codepath which can result in it not being invoked.

[BrendanFDMoore]

Personally I'd prefer a consistent await-able function, but I can see the value in supporting non-async Buffers as an option.

Could the promisify be handled internally? ie, always return a Promise, but if a Buffer is detected, do the processing in the initial Promise setup before returning, then just resolve with the value immediately.

edit: meant to comment on the proposal issue, not this one. Oops. Sorry.