If you were looking to just get the month name from the month number, you could use this:
var str = "2017-11-22"; // this would be your date
var res = str.split("-"); // turn the date into a list format (Split by / if needed)
var months = ["Jan", "Feb", "March", "April", "May", "June", "July",
"August", "September", "October", "November", "December"]; // empty first value because it starts at 0
console.log(months[res[1]-1]) // month name
JSFiddle: https://jsfiddle.net/p8fwhydc/1/