[whatwg] link.sizes and [PutForwards=value]

Mon Aug 1 11:29:04 PDT 2011

On Sat, Jul 30, 2011 at 12:51 AM, Cameron McCormack <cam at mcc.id.au> wrote:
> There is a disadvantage.  In JS, doing a comparison between two objects,
> regardless of whether they have custom stringification behaviour, will
> compare based on object identity and not the string.
>
> <!DOCTYPE html>
> <iframe id=x src=b.html></iframe>
> <iframe id=y src=b.html></iframe>
> <script>
> window.onload = function() {
>  var xw = document.getElementById("x").contentWindow;
>  var yw = document.getElementById("y").contentWindow;
>  alert([xw.location, yw.location,
>          xw.location == yw.location].join("\n"));
> };
> </script>
>
> The two Location objects stringify to the same thing, but are not ==.  I
> think this can be confusing.

It's a confusion shared by all objects, though:

var x = [1,2];
var y = [1,2];
alert([x,y,x==y).join(' ');

This alerts "1,2 1,2 false".

Unfortunately, object equality is of fairly limited usefulness in JS.

~TJ