getMonth.js (example)

getMonthExample1.js

function monthName() {
  switch (new Date().getMonth()) {
  case 0:
    return "January";
  case 1:
    return "February";
  case 2:
    return "March";
  case 3:
    return "April";
  case 4:
    return "May";
  case 5:
    return "June";
  case 6:
    return "July";
  case 7:
    return "August";
  case 8:
    return "September";
  case 9:
    return "October";
  case 10:
    return "November";
  case 11:
    return "December";
  }
  return "Unknown";
}

getMonthExample2.js

const monthNames = [
  "January", 
  "February", 
  "March", 
  "April", 
  "May",
  "June",
  "July", 
  "August", 
  "September", 
  "October", 
  "November", 
  "December"
];

function monthName() {
  return monthNames[new Date().getMonth()];
}

Note that there are other libraries via ECMAScript and 3rd party that makes this even easier. but the above are pure old school JS ways.