Getting the previous month's first date from current date in JavaScript

Question

Straightforward enough, with the date methods:

  var x = new Date();
  x.setDate(1);
  x.setMonth(x.getMonth()-1);

Simplest way would be:

var x = new Date();
x.setDate(0); // 0 will result in the last day of the previous month
x.setDate(1); // 1 will result in the first day of the month

Deals with updating year when moving from January to December

var prevMonth = function(dateObj) {
	var tempDateObj = new Date(dateObj);

	if(tempDateObj.getMonth) {
		tempDateObj.setMonth(tempDateObj.getMonth() - 1);
	} else {
		tempDateObj.setYear(tempDateObj.getYear() - 1);
		tempDateObj.setMonth(12);
	}

	return tempDateObj
};

var wrapper = document.getElementById('wrapper');

for(var i = 0; i < 12; i++) {
	var x = new Date();
  var prevDate = prevMonth(x.setMonth(i));
	var div = document.createElement('div');
  div.textContent = 
  "start month/year: " + i + "/" + x.getFullYear() +
  " --- prev month/year: " + prevDate.getMonth() +
  "/" + prevDate.getFullYear() +
  " --- locale prev date: " + prevDate.toLocaleDateString();
  wrapper.appendChild(div);
}

<div id='wrapper'>
</div>

This worked for me

var curDateMonth = new Date();
var prvDateMonth = new Date(curDateMonth.getFullYear(),curDateMonth.getMonth()-1,curDateMonth.getMonth());
console.log(curDateMonth.toLocaleString('en-US', { month: 'long' }) +' vs '+ prvDateMonth.toLocaleString('en-US', { month: 'long' }));