(maint) only add chart if it's not there

[jeffweiss]

Prior to this commit, Dashboard would experience a weird bug where
the charts would intermittantly show up twice. This commit adds a simple
exists? check and only adds the charts if they are not already in the
DOM.

[puppetcla]

CLA Signed by jeffweiss on 2012-01-27 21:00:00 -0800

[sodabrew]

Was this always the case, or did it begin with the new jqPlot code? Could there be a fix to the root cause?

[jeffweiss]

I don't know. I also didn't see it for several days of using @fhrbek's charting. Then, when it came time for me to give a demo, it showed up and wouldn't go away, irrespective of development or production modes or asset precompilation. I also tried checkin out fresh copy of repo. Stepping through JavaScript only added it once, but when nothing was left to step through, a second magically appeared. JavaScript is definitely not my forte, so there might be a more elegant solution.

[sodabrew]

I found that if I run rake assets:precompile, I get double charts.

[jeffweiss]

Cool. Glad it's not just me. :)

[sodabrew]

Yep, it's definitely the assets:precompile. Basically if you have both of these settings, you'll get the individual uncompressed JS and CSS files, as well as the coalesced and minified versions:

  config.assets.compile = true
  config.serve_static_assets = true

There's a small headache that because we do have assets in public/ that need to be served in dev mode, we cannot simply switch off serve_static_assets in config/environments/development.rb. I don't see an obvious setting like "don't link to public/application.js in dev mode".

[sodabrew]

The epic saga starts at rails/rails#6421

My suggestion is to close this PR with a mental note that in dev mode, run bundle exec rake assets:clean after testing bundle exec rake assets:precompile.

[jeffweiss]

Noted. Thanks.