Am I losing my mind, or is there glaring bug in the Google Annotated Timeline?

Question

I see Google's example code listing dates for January, but the chart is displaying dates for February!

On my test machine, it is doing the same thing. I've told it to display dates for September, but it is displaying dates for October instead!

Can anyone else confirm this as happening?

http://code.google.com/apis/visualization/documentation/gallery/annotatedtimeline.html

Answer 1

No, you're not losing your mind. The month in the Javascript Date object is zero-indexed. That means:

0  = January
1  = February
2  = March
3  = April
4  = May
5  = June
6  = July
7  = August
8  = September
9  = October
10 = November
11 = December

Answer 2

The months in the javascript date are 0 based not 1 based. So 0 is Jan, 1 is Feb, etc. See http://www.w3schools.com/js/js_obj_date.asp and you might want to check out http://en.wikipedia.org/wiki/Off-by-one_error

Answer 3

ECMA-262 5ed, pp.165:

15.9.1.4 Month Number

Months are identified by an integer in the range 0 to 11, inclusive.