Show rectangles inside the chart. This option accepts array including object that has axis, start, end and class. The keys start, end and class are optional. axis must be x, y or y2. start and end should be the value where regions start and end. If not specified, the edge values will be used. If timeseries x axis, date string, Date object and unixtime integer can be used. If class is set, the region element will have it as class.
external List<RegionOptions> get regions;
external set regions(List<RegionOptions> v);