Converting single file revealing module pattern javascript to multi-file using import

I am new to JS design patterns and have not used much of require or import. I have a single module which contains multiple functions and private variables, which is packaged into a module. Currently everything is in one file but splitting it into multiple files would be good practice and provide better clarity. The simplified view of the module's pattern looks something like this:

let Module = () => {
  //some private variables
  let private1,
      private2;

  //some public functions
  function addDatatoPrivate1 (data) {
    private1 = processData(data);
  }

  function addDatatoPrivate2 (data) {
    private2 = processData(data);
  }

  //private function processData
  function processData(data) {
    return data.trim();
  }

  return {
    addDatatoPrivate1: addDatatoPrivate1,
    addDatatoPrivate2: addDatatoPrivate2,
  }
}

I would like to split up the functions into multiple files i.e. separate file for addDatatoPrivate1, addDatatoPrivate2 and processData. In addition I would like to have the variables private1 and private2 be available for other methods in the Module privately. How do I go about splitting the code into multiple files and then how to use import to get the different components of the module to package into one.

The eventual aim is to have something which a user can load into their own project and use something like d3js or jQuery. For example, with the code as above anyone can simply assign the module to a variable and use it like so:

  let moduleInstance = Module();
  moduleInstance.addDatatoPrivate1(' some data here ');
  moduleInstance.addDatatoPrivate2(' some data here2 ');