Now that we've moved the logic to generate the events data to a model,
and we've got access to the model in the component rendering the chart,
we can render the data inside the chart instead of doing an extra AJAX
request to get the same data.
Originally, this was problaby done this way so the page wouldn't take
several seconds to load while preparing the data for the chart when
there are thousands of dates being displayed. With an AJAX call, the
page would load as fast as usual, and then the chart would render after
a few seconds. However, we can have an even better performance
improvement in this scenario if we use a Set instead of an Array. The
method `Array#include?`, which we were calling for every date in the
data, is much slower that `Set#merge`. So now both the page and the
chart load as fast as expected.
We could also use something like:
```
def add
(...)
shared_keys.push(*collection.keys)
end
def build
(...)
shared_keys.uniq.each do |k|
(...)
end
def shared_keys
@shared_keys ||= []
end
```
Or other approaches to avoid using `Array#include?`. The performance
would be similar to the one we get when using `Set`. We're using a `Set`
because it makes more obvious that `shared_keys` is supposed to contain
unique elements.
We've had some tests failing in the past due to these AJAX requests
being triggered automatically during the tests and no expectations
checking the requests have finished, so now we're reducing the amount of
flaky tests.
For now we're only adding rules related to spacing and double quotes,
following the same rules we use in Ruby, which are the same rules
CoffeeScript followed when compiling these files.
We're also using the recommended ESLint rules, which will warn us about
many JavaScript common pitfalls, the `strict` rule which enforces using
strict mode, and the `no-console` rule, which will prevent us from
shipping code meant for debugging.
Although it's arguably more common to use the JSON format to define
these rules, I've chosen YAML because it's the format we use in all our
linters.
These statements were automatically added by CoffeeScript.
I'm only removing the obvious cases; there might be more cases where the
`return` statement isn't necessary.
