[StyleGuide] Allow let in JavaScript code

[StyleGuide] Allow let in JavaScript code

In https://codereview.chromium.org/2466263003 we realized that we should think
about our strategy for allowing `let` in Catapult. charliea@ proposed three
options for moving to allow it:

* Allow `let` but don't recommend it
* Recommend it for new code, but not for old code
* Recommend it for new code and require fixes to old code as it is modified.

On the basis that block scoping is a win for developer productivity, it makes
sense to recommend `let` in at least some cases, which throws out the first
option.

Given that requiring fixes to old code will almost certainly annoy
people, and the promise of --fix one day working with processors, that seems to
leave the second option as the best possible one.

BUG=catapult:#2833

Review-Url: https://codereview.chromium.org/2621643003
Committed: https://chromium.googlesource.com/external/github.com/catapult-project/catapult/+/98ef250d15b5d10ea61de27268f830cb07ca48a2

[eakuefner, 2017-01-09 22:36:59]

eakuefner@chromium.org changed reviewers:
+ benjhayden@chromium.org, charliea@chromium.org

[eakuefner, 2017-01-09 22:36:59]

PTAL.

[charliea (OOO until 10-5), 2017-01-12 18:29:27]

lgtm

I'm assuming we'll allow people to migrate old code to use it, but won't
explicitly encourage it when submitting CLs that touch that code?

[benjhayden, 2017-01-12 18:58:25]

lgtm

[eakuefner, 2017-01-12 19:04:00]

On 2017/01/12 at 18:29:27, charliea wrote:
> lgtm
> 
> I'm assuming we'll allow people to migrate old code to use it, but won't
explicitly encourage it when submitting CLs that touch that code?

Yes, that's my understanding as well.

[eakuefner, 2017-01-12 19:04:06]

The CQ bit was checked by eakuefner@chromium.org

[commit-bot: I haz the power, 2017-01-12 19:04:10]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-12 19:05:19]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-01-12 19:05:20]

Try jobs failed on following builders:
  Catapult Linux Tryserver on master.tryserver.client.catapult (JOB_FAILED,
https://build.chromium.org/p/tryserver.client.catapult/builders/Catapult%20Li...)
  Catapult Presubmit on master.tryserver.client.catapult (JOB_FAILED,
https://build.chromium.org/p/tryserver.client.catapult/builders/Catapult%20Pr...)

[eakuefner, 2017-01-27 18:02:54]

The CQ bit was checked by eakuefner@chromium.org

[eakuefner, 2017-01-27 18:02:55]

The patchset sent to the CQ was uploaded after l-g-t-m from
benjhayden@chromium.org, charliea@chromium.org
Link to the patchset: https://codereview.chromium.org/2621643003/#ps40001
(title: "rebase")

[commit-bot: I haz the power, 2017-01-27 18:03:00]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-27 18:24:02]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1485540174568310,
"parent_rev": "3c9b30e0cc0d45d6728dec4440585ffd3ac89b2a", "commit_rev":
"98ef250d15b5d10ea61de27268f830cb07ca48a2"}

[commit-bot: I haz the power, 2017-01-27 18:24:05]

Description was changed from

==========
[StyleGuide] Allow let in JavaScript code

In https://codereview.chromium.org/2466263003 we realized that we should think
about our strategy for allowing `let` in Catapult. charliea@ proposed three
options for moving to allow it:

* Allow `let` but don't recommend it
* Recommend it for new code, but not for old code
* Recommend it for new code and require fixes to old code as it is modified.

On the basis that block scoping is a win for developer productivity, it makes
sense to recommend `let` in at least some cases, which throws out the first
option.

Given that requiring fixes to old code will almost certainly annoy
people, and the promise of --fix one day working with processors, that seems to
leave the second option as the best possible one.

BUG=catapult:#2833
==========

to

==========
[StyleGuide] Allow let in JavaScript code

In https://codereview.chromium.org/2466263003 we realized that we should think
about our strategy for allowing `let` in Catapult. charliea@ proposed three
options for moving to allow it:

* Allow `let` but don't recommend it
* Recommend it for new code, but not for old code
* Recommend it for new code and require fixes to old code as it is modified.

On the basis that block scoping is a win for developer productivity, it makes
sense to recommend `let` in at least some cases, which throws out the first
option.

Given that requiring fixes to old code will almost certainly annoy
people, and the promise of --fix one day working with processors, that seems to
leave the second option as the best possible one.

BUG=catapult:#2833

Review-Url: https://codereview.chromium.org/2621643003
Committed:
https://chromium.googlesource.com/external/github.com/catapult-project/catapu...
==========

[commit-bot: I haz the power, 2017-01-27 18:24:06]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/external/github.com/catapult-project/catapu...

[lpy, 2017-01-27 18:24:56]

Awesome! Thank you!