Aurelia polyfills are enumerable

[jods4]

When you simply assign the prototype, like so:
Array.prototype.includes = function...
You introduce a new enumerable member for all arrays.

So if someone had written code like this:

for (var i in myArray) {
  var v = myArray[i];
  // do whatever with v
}

It's very likely to now break, because "includes" will be an iteration of i.

This is a regression wrt previous releases that used corejs. I didn't check but I guess that CoreJs defines a non-enumerable property for its polyfills.

[EisenbergEffect]

Well, you shouldn't use a for/in loop with an array ;) But, we'll get it fixed.

[jods4]

I was sure you would say that. 😉

I don't approve but I'm not the only committer to our code base...
FWIW, this was considered common enough that recently the TS team has taken special steps to support this pattern...

[EisenbergEffect]

We'll fix it. I'm looking at it now. No problem :)

[jods4]

Reading my comment above I realize it was ambiguous... For the record I don't approve the practice of for..in over arrays, not your comment ;)

Just sayin': a quick glance over the code shows that string.js has the same problem, although it's certainly a lot less likely to trigger issues. I know of noone who does for (var i in "troll").

[EisenbergEffect]

Yeah, I understood your meaning :) I fixed the array issues but wasn't sure if it was worth it to fix the string issues. It's not that big a deal though. I could do it.