I want to list out the months of the year using a JavaScript array, but I am stuck on how to make Jan month 1 instead of month 0

Question

Like the question says, I am trying to list the months of the year with the corresponding abbreviation of the month name, but I am stuck on how to make the alert print 'Month 1 is Jan' instead of 'Month 0 is Jan'. This is my code within tags in my code, and the result is this. How can I get the result to begin from Month 1 for January? Thanks

        var months =["Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"];
        var message = "";
        for (i in months) {
            message += 'Month ' + i + ' is ' + months[i] + '\n';
        }
        alert(message);

I'm voting to close this question as off-topic because it shows no effort solving the issue. — ceejayoz, Jun 16 '16 at 19:31
I literally spent almost an hour on it and all I was missing was parantheses around the i + 1.... — theJcode24, Jun 16 '16 at 19:33
Wait the answer wasnt even adding the (i+1).... now it says Month 01 is Jan, Month 11 is Feb, Month 21 is Mar, etc... help please — theJcode24, Jun 16 '16 at 19:37
@ceejayoz how come you dont try to help people who are new instead of accusing them of not trying? I literally spent the last hour on this one problem.. — theJcode24, Jun 16 '16 at 19:39
@nicael It's not quite as simple as it looks. `for..in` is just the wrong kind of iterator. — 4castle, Jun 16 '16 at 19:49

4castle · Accepted Answer · 2016-06-16T19:54:22.457

2

Don't use a for..in loop to iterate an array. It's designed to iterate over object keys, and will make i be a string (hence why i + 1 isn't working).

Use a normal for loop:

var months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
var message = "";
for (var i = 0; i < months.length; i++) {
  message += 'Month ' + (i + 1) + ' is ' + months[i] + '\n';
}
alert(message);

edited Jun 16 '16 at 19:54

answered Jun 16 '16 at 19:41

4castle

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Wow thanks so much for the answer! I tried changing to a while or do while loop, but I didn't think about the regular for loop. – theJcode24 Jun 16 '16 at 19:47
Btw you can convert a string easily to a number with the unary plus `+i`, but there are still [several reasons](http://stackoverflow.com/a/3010848/5743988) not to use `for..in` with arrays. – 4castle Jun 16 '16 at 20:05
Sorry what is a unary plus `+i`? – theJcode24 Jun 17 '16 at 07:07
Read [this](http://stackoverflow.com/a/5450116/5743988). When you put a plus `+` next to a variable, it converts the variable to a number type. So `+i` would convert `i` to a number. When you were using the `for..in` loop, one option would have been to do `(+i + 1)` – 4castle Jun 17 '16 at 12:19

I want to list out the months of the year using a JavaScript array, but I am stuck on how to make Jan month 1 instead of month 0

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