console.log("%%") prints only one %

[adon-at-work]

console.log("%%");  // prints only one % in console

Expected behavior is to print two % signs
Problem reproducible in v0.12.7 and v0.10.36. But not in v4.2.1

Current Workaround: use process.stdout.write(msg + '\n');
Any chance this bug be patched in v0.12 or older versions? Thanks!!

[rvagg]

The documentation for console.log() will point you to util.format() where this is explained. This is expected behaviour and not a bug.

[adon-at-work]

@rvagg, I think this is tricky. :)

First, there exists a different behavior in v4.2.1 (prints two %) and v0.12.7 (prints one %).
Google Chrome and Firefox also prints two % signs.

MOST IMPORTANTLY, from the the documentation you shared, it says:

If the placeholder does not have a corresponding argument, the placeholder is not replaced.

Appreciate if you can take another look on this problem

[rvagg]

reopening, you're right and I wasn't aware of the discrepancy

[rvagg]

I haven't found where this changed but my guess is that it was a breaking change and I don't see it being backported to anything prior to v4.x. I'll look to others for input on this.

[adon-at-work]

Thanks @rvagg. I guess it really depends on whether there exists a second parameter for console.log()

[rvagg]

214d0204 this looks like a bug to me /cc @ChALkeR

[adon-at-work]

214d0204 seems relevant. although it's initially meant for speed improvement, that exactly also followed the behavior of latest browsers (Chrome and Firefox). Wish it could be backported to v0.12? But will leave you all to decide. Or, at least consider adding some warnings in the doc.

@rvagg, thanks again for the prompt and relevant responses. 👍

[ChALkeR]

Hm. First thing to note here: the current behaviour for a single string is correct, and if 214d020 changed it — it fixed it. The problem was that I wasn't aware of such a bug.

This actually makes 214d020 a semver-major, and that change should probably be hightlighted.

[ChALkeR]

@rvagg Browsers print %% in console.log('%%').

[ChALkeR]

@adon-at-work As for 0.10 and 0.12 — I doubt that it's worth backporting this change.

[adon-at-work]

FYI. It hurts our use cases which make use of console.log() just like a stdout dump.

I actually expected its behavior to be like how process.stdout.write() is introduced.
See https://nodejs.org/api/process.html#process_process_stdout

Hint for another doc fix? if not backporting

[ChALkeR]

@adon-at-work About backporting — it was a personal opinion. Not sure what the others think.
/cc @nodejs/collaborators

[adon-at-work]

no worries. pls determine what will work best according to the usual practices 👍