... 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 <bruan...@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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