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.

[Christoph267811690l1g]

same issue here in 2024.

resetting preferences did not solve it but
Edit -> Purge -> All Memory And Disk Cache ... did resolve it

in case this does not resolve it, you can manually write the array prototype functions in case they are missing:

// Polyfill for .map() if it doesn't exist
if (!Array.prototype.map) {
    Array.prototype.map = function(callback, thisArg) {
        var T, A, k;
        if (this == null) {
            throw new TypeError(" this is null or not defined");
        }
        var O = Object(this);
        var len = O.length >>> 0;
        if (typeof callback !== "function") {
            throw new TypeError(callback + " is not a function");
        }
        if (arguments.length > 1) {
            T = thisArg;
        }
        A = new Array(len);
        k = 0;
        while (k < len) {
            var kValue, mappedValue;
            if (k in O) {
                kValue = O[k];
                mappedValue = callback.call(T, kValue, k, O);
                A[k] = mappedValue;
            }
            k++;
        }
        return A;
    };
}

// Polyfill for .includes() if it doesn't exist
if (!Array.prototype.includes) {
    Array.prototype.includes = function(searchElement, fromIndex) {
        var O = Object(this);
        var len = parseInt(O.length, 10) || 0;
        if (len === 0) {
            return false;
        }
        var n = parseInt(fromIndex, 10) || 0;
        var k;
        if (n >= 0) {
            k = n;
        } else {
            k = len + n;
            if (k < 0) {
                k = 0;
            }
        }
        while (k < len) {
            if (O[k] === searchElement) {
                return true;
            }
            k++;
        }
        return false;
    };
}