Bar length in milliseconds

Right now we can specify bar lengths in milliseconds on date axes but this is interpreted in a browser-timezone-dependent manner, which seems like a clear bug that makes this feature unusable. See https://codepen.io/nicolaskruchten/pen/qBOKdQG …

Basically, the following figure JSONs (which differ only in x) should probably have the same output, regardless of timezone of browser:

{
"data":[{"base":["2020-02-06 00:00"],"orientation":"h","type":"bar",
"x":[86400000],"y":[1]}],
"layout":{"xaxis":{"type":"date"}
}
}

{
"data":[{"base":["2020-02-06 00:00"],"orientation":"h","type":"bar",
"x":["1970-01-02 00:00"],"y":[1]}],
"layout":{"xaxis":{"type":"date"}}
}

[nicolaskruchten]

Done.

[alexcjohnson]

One thing that will come up then sometimes is that all your y values (in default orientation) would be numbers and all your base values would be dates… I think we should auto-detect the xaxis.type to date in this case… thoughts?

Assuming you meant yaxis.type then yes, that sounds right. Basically, if there’s a base on bar traces, use that for autotype rather than y (in default orientation 😉).

Let’s move this to at least a minor.

As a tightly-scoped issue this is unambiguously a bug. Of course it will need careful testing but I think it’s fine in a patch.