How do I make a copy backup of an Indeisgn file with a script and rename it?

I know about backing up IDML files, but for large files, I think it would be faster to copy the indd file directly.

I want to copy the current indd file directly to the “Backup” directory in the same level directory and rename it.
Like this:
aa.indd
After the backup:
... \Backup\2025-03-03-aa.indd

Some of the code below is for backing up IDML files and it works fine.

I want to add copy indd file to Backup and change the name .
Please advise how to modify it.
Thanks a lot.

var myDate = new Date();
var myYear = myDate.getFullYear();
var myMonth = ("0" + (myDate.getMonth() + 1)).slice(-2); // Add leading zero
var myDay = ("0" + myDate.getDate()).slice(-2); // Add leading zero
var myFormattedDate = myYear + "-" + myMonth + "-" + myDay;
/**
* Creates a folder inside of the active document’s parent folder 
* @ param the active document 
* @ return the folder’s path 
* 
*/
saveIDML();
function saveIDML() {

		//creat Backup folder
		var myPathName = app.activeDocument.filePath.fsName + '/' + 'Backup';
		var mySFolder = Folder(myPathName);
		try {
			//  Create backup folder
			mySFolder.create();	

    var idmlPath =  app.activeDocument.filePath.fsName.replace(/\\/g,'/')+'/'+"backup"+'/'+myFormattedDate+"-"+app.activeDocument.name.replace(/\.indd|\.indt/g,'.idml');

    app.activeDocument.exportFile(ExportFormat.INDESIGN_MARKUP, idmlPath, false);
    }
	catch(e)
	{
		alert("Problem when creating the folder")
	}
}