Array extras and Objects

Andrea Giammarchi andrea.giammarchi at gmail.com
Thu Dec 1 08:00:33 PST 2011


... iterators not backward compatible ... a failing solution for me for
this very simple and common problem :-/

On Thu, Dec 1, 2011 at 2:04 PM, David Bruant <bruant.d at gmail.com> wrote:

> Le 01/12/2011 08:47, Andrea Giammarchi a écrit :
> > Let's say this is an attempt to bring some new, easy to implement,
> > method for the native Object.prototype
> > Specially about forEach, the most used Array.prototype method out there,
> That's quite an ambitious statement. I use forEach, but I think I use
> push, concat, every/some, map and reduce quite often as well and I
> wouldn't be able to tell which I use more often (probably push).
>
> > it's quite clear JS developers would like to have similar method to
> > iterate over objects, as key:value pairs rather than index:value.
> It seems that iterators [1] could do what you need. In this proposal (so
> very likely to be in ES.next), you can see this example:
> -----
> for ([key, val] of items(x)) {
>    alert("x." + key + " = " + val);
> }
> -----
>
> There is even the possibility for you to define your own iterator on
> your objects.
>
> > Almost every framework/library out there has an "error prone"
> > each(obj, callback) method, able to automagically recognize if the
> > passed obj is an array, an arrayLike, or an object.
> > A classic failing scenario is a function used as object, where the
> > length property won't mean it's an arrayLike entity.
> If some library authors think that an array is an object with a 'length'
> property, I think that they should learn JavaScript and that is not a
> reason to add a language feature.
>
> David
>
> [1] http://wiki.ecmascript.org/doku.php?id=harmony:iterators
>
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