How to get date of last september dynamically with moment.js

Question

I need the date of last September with moment.js - but dynamically.

Current Date

currentDate:string = moment().format('YYYY-MM'); // This will be 2017-10

How to know when the last september was from the current date? I need somethink like this:

lastSteptember = moment(this.currentDate).getDateOfLast('september').format('YYYY-MM');

So the result from now would be:

2017-09

But 3 months ago the result would have been another:

2016-09

How do I can handle this with moment.js?

Answer 1

I found a pretty solution and solved it like this:

currentYear: number = moment().year();
lastYear: number = moment().subtract(1, 'years').year();
nextYear: number = moment().add(1, 'years').year();

if(moment().isSameOrAfter(this.currentYear + '-09-01', 'month')) {
  this.currentServiceYearStartDate = this.currentYear + '-09-01';
  this.currentServiceYearEndDate = this.nextYear + '-08-31';
} else {
  this.currentServiceYearStartDate = this.lastYear + '-09-01';
  this.currentServiceYearEndDate = this.currentYear + '-08-31';
}

console.log('Startdate: ' + this.currentServiceYearStartDate);
console.log('Enddate: ' + this.currentServiceYearEndDate);

https://momentjs.com/docs/#/query/is-same-or-after/