Worth noting, that adding a month the naive way won't always get you what you should expect... for example:
let dtm = new Date(2020,0,31); // Fri Jan 31 2020...
dtm.setMonth(dtm.getMonth() + 1);
console.log(dtm);
// Mon Mar 02 2020...
That's not what you should expect, I would expect the last day of February.
function addMonths(dtm, months = 1) {
const month = dtm.getMonth() + ~~months;
const ret = new Date(dtm); // clone date - don't mutate
ret.setMonth(month);
if (ret.getMonth() > month) {
ret.setDate(0); // go to end of previous month
}
return ret;
}
This way you can add to the date, without mutation and get the expected result.
let dtmIn = new Date(2020,0,31);
let dtmOut = addMonths(new Date(2020,0,31));
console.log(dtmOut);
// Sat Feb 29 2020...
Worth noting, that adding a month the naive way won't always get you what you should expect... for example: let dtm = new Date(2020,0,31); // Fri Jan 31 2020... dtm.setMonth(dtm.getMonth() + 1); console.log(dtm); // Mon Mar 02 2020... That's not what you should expect, I would expect the last day of February. function addMonths(dtm, months = 1) { const month = dtm.getMonth() + ~~months; const ret = new Date(dtm); // clone date - don't mutate ret.setMonth(month); if (ret.getMonth() > month) { ret.setDate(0); // go to end of previous month } return ret; } This way you can add to the date, without mutation and get the expected result. let dtmIn = new Date(2020,0,31); let dtmOut = addMonths(new Date(2020,0,31)); console.log(dtmOut); // Sat Feb 29 2020...