function test(_config) {
const markDates = _config.markDates;
const overallDates = _config.overallDates ? _config.overallDates : {};
const firstDay = overallDates.start
? overallDates.start
: new Date(
Date.UTC(
markDates[0].start.getUTCFullYear(),
markDates[0].start.getUTCMonth(),
1
)
);
const lastDay = overallDates.end
? overallDates.end
: new Date(
Date.UTC(
markDates[markDates.length - 1].end.getUTCFullYear(),
markDates[markDates.length - 1].end.getUTCMonth(),
1
)
);
return d3.utcDay();
}