Why does the month argument range from 0 to 11 in JavaScript's Date constructor?

Question

When initializing a new Date object in JavaScript using the below call, I found out that the month argument counts starting from zero.

new Date(         


        

Answer 1

I know it's not really an answer to the original question, but I just wanted to show you my preferred solution to this problem, which I never seem to memorize as it pops up from time to time.

The small function zerofill does the trick filling the zeroes where needed, and the month is just +1 added:

function zerofill(i) {
    return (i < 10 ? '0' : '') + i;
}

function getDateString() {
    const date = new Date();
    const year = date.getFullYear();
    const month = zerofill(date.getMonth()+1);
    const day = zerofill(date.getDate());
    return year + '-' + month + '-' + day;
}

But yes, Date has a pretty unintuitive API, I was laughing when I read Brendan Eich's Twitter.