$.ajax().then((data)=>{
    let excel = createObjectURL(data);
    //donwloadahrefexcelLink
})

probably restore what you want to do

when I did the download function, it was implemented like this:
request the backend interface after clicking "download". The backend API sets the header-related content when returning the data stream, so that the browser can download the file automatically according to the content returned.
my previous interface is written in Node.js. I'll give you a reference

 res.set({
      'Content-Type': 'XXX',
      'Content-Disposition': 'XXXX' 
 });

you can search the setting method of Content-Type and Content-Disposition

get request to try whether it can be downloaded directly with a tag

https://github.com/azl3979858.

import writer from 'file-writer';
writer('a.csv', '\
year,age,status,sex,population\r\n\
1850,20,0,1,1017281\r\n\
1850,20,0,2,1003841\r\n\
',{})