Implement console.group

[Rich-Harris]

It might be totally impractical to do this properly, so I'll understand if it's immediately closed as wontfix, but a) it'd be really useful, and b) @domenic sent me here!

Basically, it'd be really great if there was something vaguely equivalent to console.group, as it's incredibly useful for debugging in the browser. I whipped up node-console-group which is a very naive implementation (can't handle wrapped lines, etc) but good enough for my current needs - does this seem like something that would be worth fleshing out and adding to io.js?

[silverwind]

This looks to be implemented in all major browsers, so +1 for parity. I think your example is a bit too fancy on whitespace, and we should probably only handle the indentation (2 chars?) and maybe add a character on the first char, like |.

[rlidwka]

What are use-cases for it?

I see this method for the first time honestly.

[Fishrock123]

This looks like it can be done in userland just fine? Is there any thing we need to better support it? Otherwise I'm -1.

[silverwind]

It can be done in userland, but what about compatibilty with scripts using these console methods? They'd unnecessarily error out.

[mscdex]

I think I'm +1 on the general idea, since we already have most other console.* functions that browsers provide.

However, I'm not sure about the proposed formatting. Perhaps there is some other layout that might scale better with nesting? Maybe we could (additionally) support some sort of level parameter like util.inspect() has?

[yosuke-furukawa]

I am +1, because we are better to implement same api on browser as possible.
BUT, console is a PANDORA box .....

DeveloperToolsWG members are trying to standardize console API.
According to the doc

node/io.js unimplemented:

• console.clear
• console.count
• console.debug
• console.dirxml
• console.table
• console.group / groupCollapsed / groupEnd
• console.isIndependentlyComposed
• console.profile/profileEnd
• console.timeline/timelineEnd
• console.timeStamp

node/io.js implemented but different behavior from browsers

• format specifier

Specifier	Description	node/io.js implement status
%s	Formats the value as a string (cooercing via toString() if necessary)	same
%d, %i	Formats the value as an integer	Formats the value as a number (not integer and %i is not implemented)
%f	Formats the value as a floating point value	not implemented but %d is implemented
%o	Formats the value as an expandable DOM Element (or JavaScript Object if it is not)	not implemented
%O	Formats the value as an expandable JavaScript Object	not implemented but %j is implemented
%c	Formats the output string according to CSS styles you provide	not implemented

We need to define what API should be implemented / should not be implemented.
And if we implement the API, we should follow the standardize API specification.

[Rich-Harris]

What are use-cases for it?

It makes logging output much more legible, especially when you have a lot of it. It's particularly useful when you have a function that gets called frequently, and you want to understand how (or if) it's being called from a particular point in your code. It's also very useful for understanding anything that happens recursively, because there's visual structure involved.

My words aren't really doing it justice, but it's a bit like going from alert() to console.log() - you can just debug a lot more efficiently.

I'm not sure about the proposed formatting

That's fair - in fact I'm not really proposing it, as such, it's just what I cobbled together this afternoon. I'm certain it can be improved.

Thanks for considering this. I totally understand the preference for userland solutions, though as @Fishrock123 notes it does necessitate monkey-patching.

[imyller]

👍 just for the parity with browsers. As stated, there does not seem to be official standard for console API, but these nearly match:

• https://developer.chrome.com/devtools/docs/console-api
• https://developer.mozilla.org/en-US/docs/Web/API/Console

I think Node should implement something code-compatible with these and then later move to standardized console API if there ever is going to be one.

[imyller]

Even Microsoft IE/Chakra JS has now console.group, console.groupCollapsed, console.groupEnd:

• https://msdn.microsoft.com/en-us/library/windows/apps/hh696634.aspx

[silverwind]

This should be quite easy to implement. The general consensus seems to be in favor.

• console.group should add one level of indentation
• console.groupEnd should remove one level of indentation
• console.groupCollapsed should be a noop in our case aliased to console.group

As for styling, I'd suggest just two spaces as a start.