JSFiddle - React, Tailwind, and code Playground

JavaScript

var months = [
  "January",
  "February",
  "March",
  "April",
  "May",
  "June",
  "July",
  "August",
  "September",
  "October",
  "November",
  "December"
]

var temp = "Date between March 2018 and June 2019";
var match = temp.match(/Date between (\S+) (\d+) and (\S+) (\d+)/);

if (match) {
	var fromMonth = match[1];
  var fromYear = parseInt(match[2], 10);
	var toMonth = match[3];
  var toYear = parseInt(match[4], 10);
  
  if (toYear >= fromYear) {
    var fromMonthIdx = months.indexOf(fromMonth);
    var toMonthIdx = months.indexOf(toMonth);

		while (toYear >= fromYear) {
      var endIdx = (toYear > fromYear) ? 12 : toMonthIdx;
    	for (var i = fromMonthIdx + 1; i < endIdx; i++) {
      	console.log(months[i] + " " + fromYear);
      }
      fromMonthIdx = -1;
      fromYear++;
    }
  }
}