SharePoint 2016. Change custom upload location to current document set

Question

I have implemented a custom upload button on a modified 'docsethomepage.aspx'. The new page shows the properties of the DS.

I would like using javascript to upload the file to this Doc set instead to the Documents Folder.

I am following the great help found in here I would 'only' need to change the path from Documents to this Document Set. The Query Strings in the URL have these IDs available:

ID, FolderCTID, List and RootFolder of which I suspect need to use.

I am trying to fiddle with the uploadFile function but so far failed. Your help much appreciated.

Code:

var fileInput ;

    $(document).ready(function()  
    {  
        fileInput = $("#getFile");  
        SP.SOD.executeFunc('sp.js', 'SP.ClientContext', registerClick);  
    });  

    function registerClick()  
    {  
        //Register File Upload Click Event  
        $("#addFileButton").click(readFile);  
    }  
    var arrayBuffer;  

    function readFile()  
    {  
        //Get File Input Control and read th file name  
        var element = document.getElementById("getFile");  
        var file = element.files[0];  
        var parts = element.value.split("\\");  
        var fileName = parts[parts.length - 1];  
        //Read File contents using file reader  
        var reader = new FileReader();  
        reader.onload = function(e)  
        {  
            console.log(e.target);
            console.log(fileName);
            uploadFile(e.target.result, fileName);  
        }  
        reader.onerror = function(e)  
        {  
            alert(e.target.error);  
        }  
        reader.readAsArrayBuffer(file);  
    }  
    var attachmentFiles;  

    function uploadFile(arrayBuffer, fileName)  
    {  
        //Get Client Context,Web and List object.  
        var clientContext = new SP.ClientContext();  
        var oWeb = clientContext.get_web();  
        var oList = oWeb.get_lists().getByTitle('Documents');  
        //Convert the file contents into base64 data  
        var bytes = new Uint8Array(arrayBuffer);  
        var i, length, out = '';  
        for (i = 0, length = bytes.length; i < length; i += 1)  
        {  
            out += String.fromCharCode(bytes[i]);  
        }  
        var base64 = btoa(out);  
        //Create FileCreationInformation object using the read file data  
        var createInfo = new SP.FileCreationInformation();  
        createInfo.set_content(base64);  
        createInfo.set_url(fileName);  
        //Add the file to the library  
        var uploadedDocument = oList.get_rootFolder().get_files().add(createInfo)  
        //Load client context and execcute the batch  
        clientContext.load(uploadedDocument);  
        clientContext.executeQueryAsync(QuerySuccess, QueryFailure);  
    }  

    function QuerySuccess()  
    {  
        console.log('File Uploaded Successfully.');  
    }  

    function QueryFailure(sender, args)  
    {  
        console.log('Request failed with error message - ' + args.get_message() + ' . Stack Trace - ' + args.get_stackTrace());  
    }  
</script>  

Answer 1

In the end this was simply achieved by updating the SP.FileCreationInformation object set url to createInfo.set_url("http://mySPServer/sites/mytest/mydocLibrary/DocSetName/myfile.txt");