HighCharts [1] and HighStock [2] (which I use extensively on my SaaS app [3] - the home page shows a real screenshot) definitely allow gaps in the data. I can only warmly recommend both! (not affiliated with them in any way, they just do a great job).

[1] http://www.highcharts.com/demo/spline-irregular-time

[2] http://www.highcharts.com/products/highstock

[3] https://www.wisecashhq.com/

Not all the libraries ignore step charts! http://dimplejs.org/examples_viewer.html?id=steps_horizontal

Step charts are a good idea. Handling missing data in general is a bit tricky and I haven't full thought through the problem.

The real-time charts are build with a timestamp component which, given a specific time granularity (second, minute, etc.), could be used to handle gaps. Basic charts might require an option to switch on/off such behavior.

In case you're interested, I've opened up a new issue in the repository: https://github.com/fastly/epoch/issues/64

Thanks for the great suggestion!

I've run into this problem a lot but end up getting around it by finding "gaps" and putting in null data manually.

that implies its possible at all to represent null in a meaningful way