On 2009-12-08, at 13:10, Mike Samuel wrote:
> All true. And yet it is not uncommon. See the bottom of this email
> for a quick survey of a number of libraries' uses of the array-like
> concept.
FWIW, Here is the (separately/simultaneously invented) definition from
OpenLaszlo:
function isArrayLike (obj:*):Boolean {
if (obj && ((obj is Array) || (obj['length'] != (void 0)))) {
var ol = obj.length;
return ((typeof(ol) == 'number' || ol is Number) &&
((ol|0) === ol) &&
(ol >= 0));
}
return false;
}
This only shows up in the debugger, and it is used to heuristicate when
inspecting an object whether to portray it as an Array (possibly with
non-numeric properties), or as an Object. It's an acknowledgement that users
do create objects that they think of as arrays. OTOH, we don't do any magic
beyond that. If a user intends an object to be treated as an array, they use
Array operations on it (including `for`, not `for in`).
I once had the vain hope that I could say:
function MyArray () {}
MyArray.prototype = [];
to create my own subclasses of Array. That might have lessened the need for
isArrayLike.
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