Get rid of jQuery use

[vidartf]

Most people are no longer fluent in jQuery, so it makes more sense to just use native DOM/JS APIs.

[codecov-commenter]

Codecov Report

Merging #390 (193871a) into master (7dacddf) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #390   +/-   ##
=======================================
  Coverage   70.54%   70.54%           
=======================================
  Files          23       23           
  Lines         893      893           
=======================================
  Hits          630      630           
  Misses        263      263           

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