Get Sitecore Context item for a page during AJAX calls

GetSitecoreContext.cs

// Get the current URL from the page where the AJAX call has been made
var url = HttpContext.Current.Request.UrlReferrer; // Note the UrlReferrer
 
// Get the context
var siteContext = SiteContextFactory.GetSiteContext(url.Host, url.PathAndQuery);

if (siteContext?.StartPath == null)
{
    throw new Exception(); // log or handle the exception
}
 
// Get the path of Home item
var homeItemPath = siteContext.StartPath;
if (!homeItemPath .EndsWith("/"))
{
   homeItemPath += "/";
}
 
// Get item path of the page
// Add using Sitecore; reference for MainUtil. It is present in Sitecore.MainUtil
var contextItemPath = MainUtil.DecodeName(url.AbsolutePath);
 
// Find virtual paths if any and remove the virtual folder from the path
if (contextItemPath.StartsWith(siteContext.VirtualFolder))
{
   contextItemPath = contextItemPath.Remove(0, siteContext.VirtualFolder.Length);
}
 
// Get the item
var fullPath = homeItemPath + contextItemPath;
return siteContext.Database.GetItem(fullPath);