The live-updating code still needs float timestamps, but
we only need them for the most recent event (so we know
the lower threshold for fetching new events). We now send
the float timestamp separately:
* in the `/log/` view, we put it in HTML content, in a <script> tag
* in the `/log_events/` view we put it in response header
The main benefit of this is smaller response sizes for the
`/log/` and `/log_events/` views.
* Switch from nouislider to simpler <input type="range">
* Move it to a sidebar
Also, fix a bug in _get_events where the "start" local variable
got clobbered, and made the date range for the Notification
query wrong.
In the "Details" and "Log" pages Healthchecks displays a list
of events (incoming pings and sent alerts). At the top of the
events list is a two- or three-way selector for selecting
the timezone for formatting event dates and times. The selector
options are "UTC", check's configured timezone, and "Browser's
time zone". The "Browser's time zone" used to be default, initial
selection for all checks.
With this change, for checks that use cron schedule, the default
selected timezone will be the check's configured timezone.
The "Browser's time zone" option is of course still there and the
user can switch to it to see dates and times in their local time.
Rationale: I semi-regularly get support requests about unexpected
or missing alerts, where the problem boil downs to a timezone
mismatch between the client and the Healthchecks server. Sometimes
the confusion seems to be caused by the user seeing ping arrival
times in their local time zone, comparing them to their cron
expression, and not realizing their server may be using a different
timezone. By switching the default display timezone to the check's
configured timezone, I hope users will be more likely to notice
discrepancies between ping arrival times, the cron schedule,
and their local clock.
For checks using simple schedules (timeout and grace), we still
default to browser's timezone for display.
If the "Ping details" dialog takes more than ~300ms to load,
show an animated progress indicator.
Also, move the loading code to a ping_details.js file
to reduce code repetition.
