Add dynamic properties to decoder

[troibe]

As mentioned in #646
The additional getAllPropertyNames method doesn't look that pretty in my eyes but apparently no such method exists in standard javascript.

[dmjio]

The delegator is some performance sensitive code, so I'm slightly worried about the Set allocation.

[troibe]

True now if the javascript code was aware which prop of the object should be decoded that could be a more performant approach.
However I guess you probably put the actual decoding in Haskell and not on the javascript side for a good reason.

[dmjio]

@developandplay yea, decoding is in Haskell so people can build their own decoders with aeson (or other).

[dmjio]

@developandplay been doing some benchmarks, seems adding this would only result in a +/- 0.1ms penalty. In some cases it is actually faster than the existing code... which is surprising.

https://jsfiddle.net/61sw9de5/

^ you basically move your mouse (or click the button) and it benchmarks the time it takes to accumulate all properties w/ both versions of the code, then displays the improvement (positive or negative).

[troibe]

Wow this is super cool. Thanks for revisiting the issue!

[dmjio]

No problem, and thanks for this patch ;)

It does seem that new Set() isn't supported in IE 11 down ...

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set#browser_compatibility

To get around this we could check the document.documentMode property.

https://www.w3schools.com/jsref/prop_doc_documentmode.asp

[dmjio]

Or we can remove the Set, and just use a regular object.

function getAllPropertyNames(obj) {                                                                                                                                                                                                 
    var props = {}; 
    ... 
    return Object.keys(props);                                                                                                                                                                                                         
}   

[troibe]

Sounds like a decent alternative.
Seems like that was the way to go when set was not a thing yet.

I would expect overshadowing to work as expected.
However it's probably better to double check that since it's the only reason we were using set in the first place.

Also let's add a comment then that we are only using it to "simulate" a set.
Now I'm curious to see if the performance is any different but I would guess no.

[dmjio]

Merged in b32d796