Dynamically create Folders by Month and Year with Google Apps Script

const onFormSubmit = ({ response }) => {

  // converts the form response into an object with camelCase properties
  // as by default they are not
  const payload = parseResponse(response.getItemResponses());

  // wrapper function that uses Google's "UrlFetchApp.fetch" API
  // to access my *external Node.js API* I have running on the ultimate courses domain
  const { pdf, filename } = fetchPDF(payload);

  // I get the "pdf" object back, along with the generated "filename"
  // so now it's time to get jiggy and insert it somewhere
  addToDriveFolder(pdf, filename);
};

const getCurrentDateNames = () => {
  // spin up the new Date object
  const date = new Date();

  // create the names with numeric prefixes
  // so they appear in the filesystem in chronological order
  const monthNames = [
    '01-Jan', '02-Feb', '03-Mar', '04-Apr', '05-May', '06-Jun',
    '07-Jul', '08-Aug', '09-Sep', '10-Oct', '11-Nov', '12-Dec',
  ];

  // date.getMonth() returns a number, so let's lookup our Array to 
  // get the correct month we're in as actual text
  // date.getMonth() for January would return 0 so we can use it to lookup the correct value
  const month = monthNames[date.getMonth()];

  // return year as a String as Apps Script "createFolder" function
  // won't accept a number for the folder name
  // P.S. date.getFullYear().toString() also works, I think this is nicer to interpolate
  const year = `${date.getFullYear()}`;

  return { month, year };
};

const addToDriveFolder = (pdf, filename) => {

  // destructure the month and year returned, the current dates!
  const { month, year } = getCurrentDateNames();

  // next we need to create or lookup the folders...
};

const addToDriveFolder = (pdf, filename) => {

  const { month, year } = getCurrentDateNames();

  const rootFolder = DriveApp.getFolderById('dK98Ka0Ksa9sLLsaKaTszIi'); // Folder ID
};

const addToDriveFolder = (pdf, filename) => {

  const { month, year } = getCurrentDateNames();

  const rootFolder = DriveApp.getFolderById('dK98Ka0Ksa9sLLsaKaTszIi');
  
  const getFolderById = (parent, name) => {
    // our "getFolder" will create or return a folder
    return DriveApp.getFolderById(getFolder(parent, name).getId());
  };

  const getFolder = (parent, name) => {
    // we need to see if the "name" already exists
    // in this "parent" folder and return it if so
    // otherwise we'll create one and return that instead!
  };
};

const addToDriveFolder = (pdf, filename) => {

  //...

  const getFolder = (parent, name) => {
    const folder = parent.getFoldersByName(name);
    if (folder.hasNext()) {
      // we've located a folder exists under this name
      const nextFolder = folder.next();
      // the issue is, there *could be* multiple folders as it's getFoldersByName, not "getFolder" (singular)
      // for some added safety I've done this and match the folder name
      // against the name that we pass in, then return it
      if (nextFolder.getName() === name) {
        return nextFolder;
      }
    }
  };

  // call getFolder and pass in our rootFolder reference and the "year"
  const yearFolder = getFolderById(rootFolder, year);
};

const addToDriveFolder = (pdf, filename) => {

  //...

  const getFolder = (parent, name) => {
    const folder = parent.getFoldersByName(name);
    if (folder.hasNext()) {
      const nextFolder = folder.next();
      if (nextFolder.getName() === name) {
        return nextFolder;
      }
    } else {
      return parent.createFolder(name);
    }
  };

  const yearFolder = getFolderById(rootFolder, year);
};

const addToDriveFolder = (pdf, filename) => {

  //...

  const getFolder = (parent, name) => {
    const folder = parent.getFoldersByName(name);
    if (folder.hasNext()) {
      const nextFolder = folder.next();
      if (nextFolder.getName() === name) {
        return nextFolder;
      }
    } else {
      return parent.createFolder(name);
    }
  };

  const yearFolder = getFolderById(rootFolder, year);
  // pass in "yearFolder" as the next layer down
  // this creates the month under the year or returns the existing month
  const monthFolder = getFolderById(yearFolder, month);
};

const addToDriveFolder = (pdf, filename) => {

  const { month, year } = getCurrentDateNames();

  const rootFolder = DriveApp.getFolderById('dK98Ka0Ksa9sLLsaKaTszIi');

  const getFolderById = (parent, name) => {
    return DriveApp.getFolderById(getFolder(parent, name).getId());
  };

  const getFolder = (parent, name) => {
    const folder = parent.getFoldersByName(name);
    if (folder.hasNext()) {
      const nextFolder = folder.next();
      if (nextFolder.getName() === name) {
        return nextFolder;
      }
    } else {
      return parent.createFolder(name);
    }
  };

  const yearFolder = getFolderById(rootFolder, year);
  const monthFolder = getFolderById(yearFolder, month);
  monthFolder.createFile(pdf).setName(filename);
};