This uses VL's vconcat to make small multiples. It works a lot like layer but stacks instead of superimposes. This is handy since it only loads the data file once, unlike one-off chart platforms like DW.
Note that when using vconcat, you need to put "width": "container" inside of the vconcat array.
This uses some config.axisY settings for better y-axis/subtitle placement. I'll also note that for both tooltips and x-axis labels, it's important to have "type": "temporal" for VL to interpret the dates.
In this instance, we 'manually vconcatenate' to use layer to overlay a 7-day average line on top of the bars.
Lastly, here it is as a layered chart. Note that type: temporal hasn't been applied - see the tooltip.