Determine numeric month based on actual moth

Question

The following script uses a switch statement to determine the numeric month based on the actual month. Is there a more succinct way (read: elegant, or less time to write) to accomplish the same result? Is there a down-side or up-side to either approach?

jsFiddle

var month = "May"; 
 var m;
 switch(month) {
 case "January":
 m = 0;
 break;
 case "February":
 m = 1;
 break;
 case "March":
 m = 2;
 break;
 case "April":
 m = 3;
 break;
 case "May":
 m = 4;
 break;
 case "June":
 m = 5;
 break;
 case "July":
 m = 6;
 break;
 case "August":
 m = 7;
 break;
 case "September":
 m = 8;
 break;
 case "October":
 m = 9;
 break;
 case "November":
 m = 10;
 break;
 case "December":
 m = 11;
 break;
 default:
 //
 }
 console.log(m); 

Answer 1

Just use an array.

var months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
var m = months.indexOf('May'); // 4

Answer 2

Or instead of an array, work it out from the date... no need for messy arrays

function getMonthFromString(monthName){
 var d = Date.parse(mon + "1, 2000");
 if( !isNaN(d) )
 {
 return new Date(d).getMonth();
 }
 return -1;
}

Answer 3

Just have your month names in an array and use indexOf to grab the index.

var monthnames = ['Jan', 'Feb', 'Mar', 'Apr']; // etc
var month = 'Mar';
var monthno = monthnames.indexOf(month);
console.log(monthno) // 2