Batch push items into a list

batch.ts

batch(items: any[], count: number, interval: number, iteratee: (item: any, index: number) => void) {
        const len = items ? items.length : 0;

        // If the count is gte the total amount, just loop through and add 
        // them all and don't bother batching.
        if (count >= len) {
            for (let i = 0; i < len; i++) {
                iteratee(items[i], i);
            }

            return;
        }

        let index = 0;

        const _batch = () => {
            const timeout = setTimeout(() => {
                let batchItems: any[];

                if (index > 0) {
                    batchItems = notifications.slice(index, count + index);
                } else {
                    batchItems = notifications.slice(0, count);
                }

                const batchItemsLen = batchItems.length;

                if (batchItemsLen > 0) {
                    index += count;

                    for (let i = 0; i < batchItemsLen; i++) {
                        iteratee(batchItems[i], i);
                    }

                    return _batch();
                }

                clearTimeout(timeout);
            }, interval);
        };

        _batch();
    }