Array.prototype functions undefined in After Effects scripts?

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;
    };
}

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.

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.

EDIT:

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

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