Using $Ajax to save filename to a scaffold

Question

I’ve been working on it but I can’t solve my problem. I have a JS code that through an input I can access a txt file and get its name. I also created a History scaffold so I can store that name.

if (passAll === true) {
   var fullPath = document.getElementById('file').value;
     if (fullPath) {
       var startIndex = (fullPath.indexOf('\\') >= 0 ? fullPath.lastIndexOf('\\') : fullPath.lastIndexOf('/'));
       var filename = fullPath.substring(startIndex);
         if (filename.indexOf('\\') === 0 || filename.indexOf('/') === 0) {
            filename = filename.substring(1);
         }
     alert(filename);
     }
}

I got an idea to use Ajax to, using the POST method, send this filename directly to the creation URL of my scaffold so I wouldn’t need to type the filename, which would be the normal way, and save automatically (Somehow, I’d appreciate it if you could explain to me how I could do this).

My big problem is how to use Ajax and where to use it in my JS? How?

I don’t know what else to add here, I believe that every scaffold created is the same, so I will not put my scaffold.