I'm working to renew some old site that uses very old jquery (for example, it does not know what the ".html()" method is. It uses .update() instead of this). When i replace the old library with a new one (the last) - all site's jquery functionality crashes... But i need to use .ajax (instead of the old ajax.request() ) to be able to get data from other site. If i leave the old library - i got "Uncaught TypeError: $.ajax is not a function" in console, but if i place the old library and the latest one - all site's old-jquery functionality crashes, but .ajax() works good.

So, how can i get a cutted buildt (something like  jQuery 3.4.0 slim build) of the latest release, but just with the implenemtation of the .ajax() function, to use only ajax() from te latest release (  jQuery 3.4.0) ?

Tnx.