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0 pointsmac117513y ago0 comments

Your comment made me look up reduce(). Just when you think you know javascript, good code like yours throws me back to researching. If I didn't see this, I would have continued to use underscorejs to do a reduce().

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kragen13y ago· 2 in thread

Hmm, with .reduce() you have:

   $('[id^=row]').toArray().reduce(function(l,r){
		return l.pipe(function(){
			return $(r).animate({opacity:opacity}, 100);
		});
	}, $.Deferred().resolve());

but without .reduce() you have:

    var pipeline = $.Deferred().resolve();
    $('[id^=row]').each(function(index, row) {
        pipeline = pipeline.pipe(function() {
            return $(row).animate({opacity:opacity}, 100);
        });
    });

(untested) which is, to my eyes at least, more readable. Just because you can do anything with .reduce() that you can do with a for loop doesn't mean you should.

utopkara13y ago

The assignment in the loop breaks the readability for me:

In the reduce case, the deferred is in the scope of the function as a named argument; which is the main advantage of using deferred in this case. In the .each loop, deferred is a variable in the outer scope. Even though it looks like it will work (need to try), I wouldn't consider it the safer and more readable solution.

kragen13y ago

I guess I think of mutating a variable repeatedly as a pretty normal thing for a loop to do, nearly the only reason for having a loop, and you can see what the data flow is from the source code. In the reduce case, you kind of have to guess what the arguments to reduce() and the anonymous function are. I mean, if you'd gotten the l and r arguments backwards in your function, could you see that from looking at the code? What if you'd gotten the arguments to reduce() in the wrong order? (And you don't get to see what the initial value is until you finish reading the function that updates it.)

I think reduce() is awesome for associative operations and in general reasonable in point-free style. But I don't think its use in this case improves readability.

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