const luhnCheck = num => {
  let arr = (num + '')
    .split('')
    .reverse()
    .map(x => parseInt(x));
  let lastDigit = arr.splice(0, 1)[0];
  let sum = arr.reduce(
    (acc, val, i) => (i % 2 !== 0 ? acc + val : acc + ((val *= 2) > 9 ? val - 9 : val)),
    0
  );
  sum += lastDigit;
  return sum % 10 === 0;
};

luhnCheck('4485275742308327'); // true
luhnCheck(6011329933655299); //  true
luhnCheck(123456789); // false

const shuffle = ([...arr]) => {
  let m = arr.length;
  while (m) {
    const i = Math.floor(Math.random() * m--);
    [arr[m], arr[i]] = [arr[i], arr[m]];
  }
  return arr;
};

const foo = [1, 2, 3];
shuffle(foo); // [2, 3, 1], foo = [1, 2, 3]

//JavaScript program to swap two variables

//take input from the users
let a = prompt('Enter the first variable: ');
let b = prompt('Enter the second variable: ');

//using destructuring assignment
[a, b] = [b, a];

console.log(`The value of a after swapping: ${a}`);
console.log(`The value of b after swapping: ${b}`);

const dragAndDropDiv = editor.container;

dragAndDropDiv.addEventListener('dragover', function(e) {
    e.stopPropagation();
    e.preventDefault();
    e.dataTransfer.dropEffect = 'copy';
});
dragAndDropDiv.addEventListener("drop",function(e){
    // Prevent default behavior (Prevent file from being opened)
    e.stopPropagation();
    e.preventDefault();
    const files = e.dataTransfer.items; // Array of all files

    console.assert(files.length >= 1);

    if (files[0].kind === 'file') {
        var file = e.dataTransfer.items[0].getAsFile();
        const fileSize = file.size;
        const fileName = file.name;
        const fileMimeType = file.type;

        reader = new FileReader();

        reader.onloadend = function(){
            editor.setValue(reader.result);
        }

        reader.readAsText(file);
    }else{
        //Maybe handle if text is dropped
        console.log(files[0].kind);
    }
});

const levenshteinDistance = (s, t) => {
  if (!s.length) return t.length;
  if (!t.length) return s.length;
  const arr = [];
  for (let i = 0; i <= t.length; i++) {
    arr[i] = [i];
    for (let j = 1; j <= s.length; j++) {
      arr[i][j] =
        i === 0
          ? j
          : Math.min(
              arr[i - 1][j] + 1,
              arr[i][j - 1] + 1,
              arr[i - 1][j - 1] + (s[j - 1] === t[i - 1] ? 0 : 1)
            );
    }
  }
  return arr[t.length][s.length];
};

levenshteinDistance('duck', 'dark'); // 2

//JavaScript program to swap two variables

//take input from the users
let a = prompt('Enter the first variable: ');
let b = prompt('Enter the second variable: ');

// XOR operator
a = a ^ b
b = a ^ b
a = a ^ b

console.log(`The value of a after swapping: ${a}`);
console.log(`The value of b after swapping: ${b}`);