undefined undefined hu
is what should be produced according to the spec.
Divergence among implementations is a good sign that there is an opportunity to
clean up this particular mess.
The current ES6 draft requires an early error for this function because it is
trying to hoist a var declaration across a block-level declaration of the same
identifier. EG,
function f() {
{
let x=1; //early error let declaration of x in a block that contains a
nested var declaration of x
{
var x=2;
}
}
}
Because let is a new feature, this restriction doesn't introduce any backwards
compatibility issues. However, for consistency, the draft also currently
applies the same let declaration restrictions to catch parameters. Your
experiment suggests that that we might actually be able to to that ...
Allen
On May 14, 2012, at 2:57 AM, Claus Reinke wrote:
> What should be the output of the following code?
>
> (function(){
>
> try {
> throw "hi";
> } catch (e) {
> var e = "ho";
> var o = "hu";
> var u;
> console.log(e);
> }
> console.log(e,u,o);
>
> }());
>
> It seems clear that the first console.log should output 'ho'.
> Implementations seem to disagree on the second console.log, though.
>
> From my current understanding of the spec, I expected:
> undefined undefined 'hu'
>
> which I consider unfortunate; especially the first 'undefined'
> was intended to demonstrate the bad effects of separating declaration from
> initialization while treating catch and function differently, in terms of
> scoping.
>
> node, opera: undefined undefined 'hu'
>
> firefox 12 complains: 'e is not defined'
>
> ie 9 outputs: houndefinedhu
>
> It looks as if firefox misses the hoisted declaration of 'e'
> (it doesn't complain about 'u', only about 'e') while ie9 somehow merges the
> declaration and the catch parameter.
>
> Claus
> _______________________________________________
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>
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