I'm a professional Magento developer from Viet Nam. I have been working with Magento for more than 5 years.
I can work with Magento 1, Magento 2, linux servers, AWS, cache system .. I can optimize magento site and servers to get fastest speed (average loading time will be from 1 - 3 seconds)
I have read your project requirement, not only JS issue, there is a server issue, I can help you fix and improve your site.
I will be more than happy to do this job for you and corporate long-term