Script for finding a Data Extension and it's folder path using SSJS. Read more here: https://sfmarketing.cloud/2019/10/14/find-a-data-extension-and-its-folder-path-using-ssjs/

ssjs-find-de-path.js

<script runat="server">
Platform.Load("core","1.1.5");  
var DEprop = //use either "Name" or "Customer Key"
var DEval = //provide either the Name or External Key
var FindDE = DataExtension.Retrieve({Property:DEprop,SimpleOperator:"equals",Value:DEval});
var FolderID = FindDE[0].CategoryID;
var DEname = FindDE[0].Name;
var list = [];
  list.push(DEname);
var path = function(id) {
    if (id> 0) {
        var results = Folder.Retrieve({Property:"ID",SimpleOperator:"equals",Value:id});
    list.unshift(results [0].Name);
        return path(results[0].ParentFolder.ID);
    } else {
        return id;
    }
};
path(FolderID);
Write(list.join("> "));
</script>