What does the ajax request in the line #221 of file index.js use for?

[yxzlwz]

I'm trying to deploy this programme on my own server, but when I click download button in the page, it warn me that download failed.

I checked F12 console, find the request started in the line #221 of file index.js is not able to access. And after I remove this request, it works well.

So I'd like to know what does it use for? Thanks.

[CatScarf]

This part of the code is now useless. The code has been removed in the new refactored version.