JavaScript closures and recursion | Hacker News Reader

JavaScript closures and recursion

stackoverflow.com

14 pointsecounysis5 comments

I'm sorry, what's so special about this bit of code?

It doesn't seem very interesting unless you weren't aware of JavaScript's functional nature, and it's actually more complicated than it needs to be, unless I'm missing something. Here's how I'd do it:

    function startSlideshow(ms) {
        var index = -1;
        var count = $(".change_link").length - 1;
        return setInterval(function() {
            index = (index + 1) % count;
            $('.slideshow').blinds_change(index);
        }, ms);
    }

I was also rather confused as to what I was supposed to be looking at and why it wasn't using setInterval.

Your script is nicer, the modulo and increment in the same line is very tidy. It's not hacker news though, is it, or am I missing something?

I like the use of modulo; I hadn't thought of that.

setInterval is definitely much more simple and clean than recursively calling setTimeout, however it doesn't illustrate what is going on under the hood or how setInterval might be implemented.

Writing a Y-combinator isn't the easiest way to write a recursive function, but it does help us learn how recursion really works.

I suppose there's nothing too special abot the code. I have never seen a very good explanation of closures in javascript, so I thought I'd share it for anyone else who might benefit from it. You are more than welcome to not be impressed. In which case you are not likely the intended audience.

Closures did indeed blow my mind when I first decided to properly look into them, having originally assumed that JavaScript was "just like a very limited Java with a couple of weird syntax quirks" ;) Ah, the perils of teaching yourself a language using really, really old web tutorials. I do wish something like PromoteJS.com had been around when I was learning...

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