Shows that bl.ocks.org is capable of running with https. Just change the URL to start with https:// or click here. The utility of https is that devices are accessible if the user permits. For example, this block from Curran Kelleher works similarly.
It’s just a copy of a piece of code I used for an overly early talk about D3 4.0 (slides of historical interest are here). Don’t look at the code as it uses v0.1 etc. deep pre-alpha versions of D3 4.0 code.