GitLab

- Create a copy of the array passed in as an argument, which will be
modified in place

- Replace 'forEach' method with 'filter' method for brevity

Check the length of the correct array

We were using the original VL observations array in the 'map' array
method. Updated to use the final version of VL observations array

Confirm that the selected drop-dowwn options are valid before fetching
the observations

Function uses options from drop-down list that have been selected by a
user to populate the appropriate observations and then draw the
appropriate chart