How to upload file in sub folder using the folderpath

Hi,

I wanted to upload the documents in a nested folder(Subfolder).

I  have a sample code: this.newFile = parentList.get_rootFolder().get_files().add(fileCreateInfo);

But this will upload to the root location of the library.

How can we upload subfolder using folder path, ex: "/Countries/US/"

We should use JSOM(ECMA) not rest services. Any help much appreciated.

Thabnks

Krishnasandeep