Use util.inspect.custom symbol if available.

[goto-bus-stop]

Ports the buffer-inspect test from Node core.
Adds a Buffer.prototype[util.inspect.custom] method, which is an alias
to Buffer.prototype.inspect. Node already doesn't have an .inspect
method on Buffers anymore, but since this module has to work in browsers
that do not have Symbols, it seems better to keep it around.

In Node, this will use the builtin util.inspect.custom symbol. In the
browser, it will use Symbol.for('util.inspect.custom'). The browser
version of util will also use the inspect-custom-symbol module in
the near future.

If nodejs/node#20857 gets merged,
Symbol.for('util.inspect.custom') will be used everywhere and the
dependency on inspect-custom-symbol could probably be dropped.

The motivation for this is API parity and the fact that Node is
removing support for the old .inspect method:
nodejs/node#20722

[feross]

Hi @goto-bus-stop,

I'm down to merge this PR. But I noticed that Node.js ended up going with Symbol.for('nodejs.util.inspect.custom') and the https://github.com/mafintosh/inspect-custom-symbol package still uses Symbol.for('util.inspect.custom'). What do you think about just skipping the package using Symbol.for directly?

Thanks for pointing out that buffer.inspect has been deprecated. We can remove that in another PR. I opened an issue here: #239

[goto-bus-stop]

Will try to update later today 👍

[feross]

LGTM

[feross]

5.4.0

[fanatid]

Not sure how this relevant and correct, but Symbol.for was available from Chrome>=40, while Symbol was from Chrome>=38
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol#Browser_compatibility

Maybe?

typeof Symbol !== 'undefined' && typeof Symbol.for === 'function'

[feross]

@fanatid Nice catch. However, Chrome 40 was released on 2015-01-21. I don't think anyone is still running that version, and we only officially support the last 2 versions of Chrome.

[feross]

@fanatid It seems like the issue you identified affects some users of Cordova on old versions of Android. #241 I guess we can include this after all since it's just slightly longer and will ensure this works in more places :)

[ljharb]

Symbol.for is a syntax error in older browsers; I filed #254 to use bracket notation to avoid that.