Little things called bugs...
Silent crash on specific data
I started the past week by investigating a bug. It can be reproduced on the current dashboard:
Updating to the latest versions of d3 and nvd3 didn't do the trick so I spent some time looking at the data and the callstack. This plot uses a library called nvd3 that is built on top of d3. The plot calls the voronoi method (voronoi layouts). This method returns an array of polygons, one for each input vertex in the specified data array. If any vertices are coincident or have NaN positions, the behavior of this method is undefined: most likely, invalid polygons will be returned.
In our case we've got points that are coincident so..we get undefined behavior. The fix is adding some random tiny noise to the data.
Tooltip undesired behavior
Sometimes, on the current dashboard, the tooltip doesn't show up. After testing for a while I realized that if you refresh the page (and get an empty svg) it works, but if you don't the tooltip might not show up. Emptying the svg resolves this problem.
Memoization
Until now we were preprocessing the data at any filter entry, no matter if we had duplicated data or not (x_x). It was about time to add some cache support. I added some caching in both dashboard.js and in telemetry.js. In dashboard.js we cache all the data that we prepared for plotting and in telemetry.js we cache all the requests made (patch here).
TinyUrl
Because we sync with all the events on the page the url may get really long so "tiny url" is a nice to have feature. I looked at the free options and picked bitly for it's jsonp call support. Because of the same-origin policy you can't make normal calls to a different domain so you either implement CORS or stick to JSONP.
New legend
A nice clean legend for several series was on my list last week. I tried to implement it with d3 and didn't get to the result I wanted so I switched to JQuery and added some d3 formatting.
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