Array.prototype functions undefined in After Effects scripts?

[Avoyt]

So, a script I was developing was working fine yesterday, but today, it seems like my Array built-in object is broken. I tried restarting After Effects to reset the environment, but it's still broken. So far, I've identified that "map", "includes", and "split" are broken, though "shift" is fine. I don't have any custom startup scripts.

I've attached a simple .txt file that demonstrates this error for me, though I'm guessing it would work normally. Just rename it to .jsx and run it yourself.

OS: MacOS Big Sur v11.4

AE: v18.4.0 build 41

[Avoyt]

EDIT:

Whoops, "split" is a string function, it won't work anyway, ahahah.

Still, "map" and "includes" are both broken for me.

[Mathias Moehl]

In general, you cannot expect Ae scripting to support all features of modern JavaScript.

After Effects scripting is using ExtendScript and ExtendScript implements the JavaScript language according to the ECMA-262 specification. This is a very old variant of JavaScript and it does not include features like Array.map, yet.

[Mathias Moehl]

The worst difference I found so far is actually this one:

true || true && false

evaluates to "false" in After Effects ExtendScript, but to "true" in modern JavaScript.

Because After Effects reads it as

(true || true) && false

whereas modern JavaScript reads it as

true || (true && false)

So when writing logic statements, make sure to always set parenthesis to avoid trouble. And don't use minifiers like uglify.js which remove these parenthesis.