Clojure's partition for arrays in Javascript

partition.js

function partition(coll, size, step, pad) {
    if (size < 1) {
        return coll;
    }
    
    function iter(acc, coll) {
        if (!coll.length) {
            return acc;
        }

        if (coll.length < size) {
            return pad ? iter(acc.concat([coll]), []) : iter(acc, []);
        }

        const part = coll.slice(0, size);
        
        return iter(acc.concat([part]), coll.slice(step));
    }

    return iter([], coll);
}