How to create list items with multiple attachment files using rest api javascript

Question

In one of user form I am using javascript rest api to create a list item with multiple attachment files. So far I am able to create list item and once created uploading an attachment file. But this is two step process first create an item and then upload
a file.
It create an additional version of the item which is not desired. Also I am not able find a way to attach multiple files in a go. Following is the code I am using.
createitem.executeAsync({
                url: "/_api/web/lists/GetByTitle('UserForm')/items(1)/AttachmentFiles/add(FileName='" + aFile.name + "')",
                method: "POST",
                contentType: "application/json;odata=verbose",
                headers: {
                    "Accept": "application/json;odata=verbose",
                    "X-RequestDigest": $("#__REQUESTDIGEST").val()
                binaryStringRequestBody: true,
                body: fileContent,
                success: fnsuccess,
                error: fnerror
So somehow I need to combine item attributes along with attachment files in body: param. I visited https://msdn.microsoft.com/en-us/library/office/dn531433.aspx#bk_ListItem but no success.
Appreciate any help.

Answer 1

Thanks Mahesh for the reply and post you share it was useful.
But this does not solve the core of the issue. You are uploading attachments after creation of item and multiple files are being attached in loop. This is kind of iterative update to an existing item with attachments. This will end up creating multiple versions. 
What I am trying to achieve is to create an item along with multiple attachments in a go. No item updates further to attach a file.
Please suggest how this can be done in one go. SharePoint does it when one creates an item with multiple attachment.
Thanks for your reply.