Extra comma considered harmful

On 19 March 2010, David Chambers wrote:

Hi Douglas,

[…] Moments ago I used JSLint for the first time; I plan to use it frequently from this point forward. I have one question, though, concerning the acceptability of extra commas. Consider the following code snippet:

var ninja = {
    name: 'Hattori Hanzou Masashige',
    shuriken: 5,
    attack: function () {
        if (ninja.shuriken) {
            ninja.shuriken -= 1;
            window.alert('Hai-Ya!');
        }
    },
};

JSLint returns an extra comma error for the unnecessary comma preceding the closing brace. I would argue, though, that this in not an error. As far as I'm aware, this comma will not cause problems.

In fact, quite the opposite is true. If one were to insert an additional property or method after attack one would not need to remember to first add a comma. In Django it's considered best practice to include a comma after every item (including the last) in a one item per line collection for this very reason.

I thought I'd give you my two cents, anyway. :)

Regards,

David Chambers

On 19 March 2010, Douglas Crockford wrote:

Your awareness is incorrect. Have you tested on IE6?

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