const head = arr => (arr && arr.length ? arr[0] : undefined);

head([1, 2, 3]); // 1
head([]); // undefined
head(null); // undefined
head(undefined); // undefined

const reverse = str => str.split('').reverse().join('');
reverse('hello world');     
// Result: 'dlrow olleh'

const gcd = (...arr) => {
  const _gcd = (x, y) => (!y ? x : gcd(y, x % y));
  return [...arr].reduce((a, b) => _gcd(a, b));
};

gcd(8, 36); // 4
gcd(...[12, 8, 32]); // 4

arr = [] // empty array
const isEmpty = arr => !Array.isArray(arr) || arr.length === 0;

// Examples
isEmpty([]); // true
isEmpty([1, 2, 3]); // false

// `date` is a `Date` object
const formatYmd = date => date.toISOString().slice(0, 10);

// Example
formatYmd(new Date());      // 2020-05-06

function filePath(file){
  let folders = file.getParents();
  const parents = [];

  function makePathString(folderArray){
    let path = "";
    folderArray.forEach((folder)=>{
      path += "/" + folder.getName();
    });
    return path;
  }
  
  while (folders.hasNext()) {
    const folder = folders.next(); //This should hopefully remove that folder from the iterator
    parents.unshift(folder);
  }

  return makePathString(parents);
}

function myFunction() {
  const myEmail = Session.getEffectiveUser().getEmail();
  Logger.log("My email is " + myEmail);
  // Log the name of every file in the user's Drive.
  var fileIterator = DriveApp.getFiles();
  const files = []; //List of [File, size] entries
  const filesMaxSize = 10;
  while (fileIterator.hasNext()) {
    var file = fileIterator.next();

    const owner = file.getOwner();

    //Only files I own
    if((!(owner)) || (!(owner.getEmail)) || owner.getEmail() != myEmail){
      continue;
    }

    const entry = [file, file.getSize()];

    function slideUp(arr, index){
      //Let's keep sliding it up so we don't have to sort it at the end.
      for(let i = index; i > 0; --i){ //Stops at 1
        const nextFile = arr[i-1];

        if(nextFile[1] > entry[1]){
          break;
        }else{
          //Swap with the next file to slide the file up
          const temp = arr[i];
          arr[i] = arr[i - 1];
          arr[i - 1] = temp;
        }
      }
    }

    if(files.length < filesMaxSize){
      files.push(entry);

      slideUp(files, files.length - 1);
    }else{
      if(entry[1] > files[files.length - 1][1]){ //If it's bigger than the smallest file in the list.
        files[files.length - 1] = entry;  //Replace the smallest file

        slideUp(files, files.length - 1); //Slide it up
      }
    }
  }

  for(let i = 0; i < filesMaxSize; ++i){
    const file = files[i][0];
    const size = files[i][1];
    Logger.log(size + "\t" + filePath(file) + "/" + file.getName() + "\t" + file.getOwner().getName());
  }
}