Array.fill and TypedArray.fill polyfills

[mvaligursky]

We got burnt on this being missing few times, and it likely gives us enough performance benefit to have the polyfill vs using the loop to work around it.

[slimbuck]

does this work correctly if Array.fill implementation was provided (not polyfilled)? might be worth splitting out the function and using it for all polyfills (including Array).

[willeastcott]

Good point.

[mvaligursky]

I would not expect a problem with this? But we only have IE to test on and that is missing both. I tested on IE and this works, and is suggested polyfill (see links I added)

[slimbuck]

I understand your test worked.

However this code suggests it's possible that Array.fill is provided by the browser while Int8Array.fill isn't. Under such a circumstance this code very well may fail.

It is simple enough to make this code not fail and I don't really understand why you don't do it?

[willeastcott]

Also, currently a bit misleading because I would expect array-fill.js to just polyfill Array#fill. I'd put the rest in typedarray-fill.js.

[Maksims]

I do understand this polyfill comes from MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/fill

But it definitely is a bit too verbose, with anti-patterns used:

1. Using of arguments leads to function deoptimisations on V8 and other engines. It is best to pre-define arguments in a function, and use them.
2. Object(o) - leads to allocations?

[mvaligursky]

@Maksims that's true, but this is just a polyfill for IE, not a generic code executing on all browsers.