Weird behaviour animating X-Axis min using timestamp

[harryray]

Hey! I've found what I think is some weird behaviour with this library, but I might just be misinterpreting.

I've set up a timeseries chart to show points across dates using the code below:

var chart = bb.generate({
    bindto: "#chart",
    data: {
		json: [
			{"date":"2021-01-01","testkey1":1,"testkey2":10,"testkey3":100},{"date":"2021-02-01","testkey1":2,"testkey2":20,"testkey3":200},{"date":"2021-03-01","testkey1":200,"testkey2":13,"testkey3":180,"testkey4":20},{"date":"2021-04-01","testkey1":300,"testkey2":10,"testkey3":190,"testkey4":36},{"date":"2021-05-01","testkey1":300,"testkey2":10,"testkey3":190,"testkey4":36},{"date":"2021-06-01","testkey1":300,"testkey2":10,"testkey3":190,"testkey4":36},{"date":"2021-07-01","testkey1":300,"testkey2":10,"testkey3":190,"testkey4":36},{"date":"2021-08-01","testkey1":300,"testkey2":10,"testkey3":190,"testkey4":36},{"date":"2021-09-01","testkey1":300,"testkey2":10,"testkey3":190,"testkey4":36},{"date":"2021-10-01","testkey1":300,"testkey2":10,"testkey3":190,"testkey4":36}		],
    	xFormat: "%Y-%m-%d",
		keys: {
			x: "date",
			value: ["testkey1","testkey2","testkey3","testkey4"]
		},
		type: "line",
	},
	axis: {
		x: {
	      tick: {
	        fit: false,
	      },
		  type: "timeseries",
		  min: "2021-01-01"
		}
	},
	  zoom: {
	    enabled: true, // for ESM specify as: zoom()

    type: "drag"
	  },
});

I've been testing and trying to figure out how to update and animate the min (in a way similar to allowing users to select 1 Year, 3 Year, 5 Year ranges to view the data with), and thought that using something like chart.axis.min({x: '2021-03-01'}) would be the answer. However, the chart.axis.min doesn't seem to take date/time formatted strings like that.

I've ended up testing a timestamp, and that also didn't work -- until I added three zeroes to the end of it. For some reason, this seems to work. For instance, 1669046646 is the timestamp for the time I'm writing this, but that wouldn't work properly in the chart (being way too small). However, 1669046646000 would.

I'm totally open to the idea that I'm misinterpreting or misreading something here - but why would adding three zeroes work? Is this a bug? A feature? Just curious!