isFirstDayOfMonth
import { isFirstDayOfMonth } from "https://esm.sh/v135/date-fns@3.6.0/index.d.mts";@example
// Is 1 September 2014 the first day of a month?
const result = isFirstDayOfMonth(new Date(2014, 8, 1))
//=> true
function isFirstDayOfMonth<DateType extends Date>(date: DateType | number | string): boolean;