Lets go a little beyond merelly hinting at the security implications:

• The files being hosted by that 3rd party are Javascript, which is code that runs on the browser.
• Barclays is a bank.

So people go to the website of a bank and their browser receives code from a 3rd party with whom the bank has no contract and who have nothing in place to obbey the level of security that is required by a banking site.

Consider the implications of getting the Barclays website to serve (from the point of view of a user) what can easilly be malware…