[whatwg] Adding ECMAScript 5 array extras to HTMLCollection
david at davidflanagan.com
Mon Apr 26 10:04:18 PDT 2010
Erik Arvidsson wrote:
>>> for (var i = 0, length = collection.length; i < length; i++)
>>> // instead of:
>>> for (var i = 0; i < collection.length; i++)
>> Actually, the former is a problem when the nodelist is modified in the
>> loop; it may result in collection[i] being undefined.
> Even when checking the length in every iteration you can run into
> problems. If you remove something earlier in the collection you will
> *miss* one item unless you fix the loop iterator.
> We should not let these edge cases get in the way of making the DOM
Rather that trying to make DOM collections feel like arrays, how about
just giving them a toArray() method? This makes it clear that a
collection is not an array, but clearly defines a way to obtain an
array. Clever implementors might even be able to optimize common
uses-cases using some kind of copy-on-write strategy so that toArray()
doesn't involve memory allocation and copying.
Of course, trying to teach programmers when they ought to call toArray()
and when it is not necessary is another matter. Perhaps calling the
method snapshot() and focusing on the live vs. static distinction
instead of the fake array vs. true array distinction would invite less
Or we can just leave the DOM as it is and get used to calling the
equivalent of Prototype's $A() function.
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