This is an example of how you can use the desk.js pagination from the last page to the first page.

pagination_LastToFirst_example.js

// get the first cases page
client.cases(function(err, cases) {
  // define a worker function that handles the
  // cases and starts over with the previous page
  // make sure you have a "callback" (doSomethingElse)
  // function defined before going into this loop
  function workCases(err, cases) {
    // test if cases is null (previous will return null
    // if there is no previous page)
    if (cases !== null) {
      // run your logic on the cases
      _.each(cases, function(case) {});
      // get the previous page
      return cases.previous(workCases);
    }
    // don't forget to finish the process with
    // doing something else.
    return doSomethingElse();
  }
  
  // start the process with the last page
  cases.last(workCases);
});