Oops, small error causing infinite loops in IE :-)
for (var i = 0; i < DontEnumsLength; i--) {
Should be
for (var i = 0; i < DontEnumsLength; i++) {
I guess unit tests would have caught that.
Andrew: I have to say, I've not seen any complaints anywhere about the
errors received when using Object.keys. Between kangax and I, the
final solution fixes two bugs. I think if you're close to releasing
1.7, it might not be worth the risk of complicating anything for these
fixes.
On Oct 22, 11:41 am, Andy E <andyearns...@gmail.com> wrote:
> That's great work. I've found myself on your blog a few times in the
> last few weeks, but I hadn't seen this. I hope you don't mind, I used
> it to update the example on my blog to:
>
> (function () {
> var hasOwnProperty = Object.prototype.hasOwnProperty,
> hasDontEnumBug = true,
> DontEnums = [
> 'toString',
> 'toLocaleString',
> 'valueOf',
> 'hasOwnProperty',
> 'isPrototypeOf',
> 'propertyIsEnumerable',
> 'constructor'
> ],
> DontEnumsLength = DontEnums.length;
>
> for (var k in {toString:null})
> hasDontEnumBug = false;
>
> Object.keys = Object.keys || function (o) {
> if (typeof o != "object" && typeof o != "function" || o ===
> null)
> throw new TypeError("Object.keys called on a non-object");
>
> var result = [];
> for (var name in o) {
> if (hasOwnProperty.call(o, name))
> result.push(name);
> }
>
> if (hasDontEnumBug) {
> for (var i = 0; i < DontEnumsLength; i--) {
> if (hasOwnProperty.call(o, DontEnums[i]))
> result.push(DontEnums[i]);
> }
> }
>
> return result;
> };
>
> })();
>
> You may notice that I sacrificed one of your optimizations for
> brevity, I'm not sure the benefits would be noticeable in every day
> use. A library like Prototype may benefit from such an optimization,
> however.
>
> by the way, I noticed that your implementation will have problems when
> walking the DontEnum properties in Internet Explorer - it looks like
> you copied and pasted the line of code from the for...in loop to your
> for loop but forgot to change the variable that was passed in to the
> iterator function.
>
> iterator.call(context || iterator, prop, object[prop]); //
> References to `prop` should be `DontEnumProperties[i]`
>
> Or store DontEnumProperties[i] in a variable for a small optimization.
>
> On Oct 21, 9:48 pm, kangax <kan...@gmail.com> wrote:
>
>
>
> > On Oct 21, 12:11 pm, Andy E <andyearns...@gmail.com> wrote:
>
> > > kangax: I was thinking the same earlier (about caching the
> > > hasOwnProperty), when I realized that my method incorrectly doesn't
> > > allow functions to be passed (not sure about Prototype's original
> > > one). I've updated the function on my blog to:
>
> > > Object.keys = Object.keys || function (o) {
> > > if (typeof o != "object" && typeof o != "function" || o === null)
> > > throw new TypeError("Object.keys called on a non-object");
>
> > > var result = [], hop = Object.prototype.hasOwnProperty;
>
> > That's better, but nothing is stopping from taking it a step further,
> > aliasing `hasOwnProperty` outside of the method.
>
> > > for (var name in o) {
> > > if (hop.call(o, name))
> > > result.push(name);
> > > }
> > > return result;
>
> > > };
>
> > > Regarding the DontEnum bug, you could work around that by checking
> > > them explicitly hasOwnProperty outside of the for...in loop.
>
> > Exactly ;)
>
> > See for example `Object.forIn()` that I experimented with a couple of
> > years ago (wow, how time flies...)
> > —http://github.com/kangax/protolicious/blob/master/experimental/object...
>
> > Looking at the code now, I would simplify it slightly, but the idea
> > holds.
>
> > [...]
>
> > --
> > kangax
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