find start Day using month and year in moment code example

Example 1: moment get month day

//The correct function to use is .date():

date.date() === 25;

Example 2: moment month start date and end date

const startOfMonth = moment().clone().startOf('month').format('YYYY-MM-DD hh:mm');
const endOfMonth   = moment().clone().endOf('month').format('YYYY-MM-DD hh:mm');