e-mihaylin

const add = n => {
  const f = x => add(n + x);
  f.valueOf = () => n;
  return f;
}

// Other Variants:
function add(n) {
  var f = function(x) { return add(n+x); };
  f.valueOf = function() { return n; };

e-mihaylin

const gcd = (a, b) => a ? gcd(b % a, a) : b;
const lcm = (a, b) => a * b / gcd(a, b);

[1, 2, 3, 4, 5].reduce(lcm); // Returns 60

e-mihaylin

const once = fn => ((...a) => {
  let executed = false;
  return (...a) => {
    if (!executed) {
      executed = true;
      return fn(...a);
    }
  };
})();

e-mihaylin

const chained = f => x => f.reduce((r, f) => f(r), x);

// chained([a,b,c,d])(input)
// yields the same result as:
// d(c(b(a(input))))

e-mihaylin

const hexToBase64 = hex => Buffer.from(hex, 'hex').toString('base64');

const hex2bin     = Object.assign( ["0000","0001","0010","0011","0100","0101","0110","0111","1000","1001"], { a:"1010", b:"1011", c:"1100", d:"1101", e:"1110", f:"1111" } ) ,
      bin2base64  = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" ,
      hexToBase64 = s => s.replace( /./g, c => hex2bin[c] ).replace( /.{1,6}/g, s => bin2base64[Number.parseInt(s.padEnd(6,0),2)] ) + "=".repeat(s.length%3) ;

e-mihaylin

const makeNumber = (n, f) => f ? f(n) : n;
const zero = f => makeNumber(0, f);
const one = f => makeNumber(1, f);
const two = f => makeNumber(2, f);
const three = f => makeNumber(3, f);
const four = f => makeNumber(4, f);
const five = f => makeNumber(5, f);
const six = f => makeNumber(6, f);
const seven = f => makeNumber(7, f);
const eight = f => makeNumber(8, f);

e-mihaylin

const numberFormat = n =>  String(n).replace(/(\d)(?=(\d{3})+(?!\d))/g, '$1,');

e-mihaylin

const fib = n => Math.round(Math.pow(((1 + Math.sqrt(5)) / 2), n - 1) / Math.sqrt(5));

e-mihaylin

const hamming = n => {
  const seq = [1];
  let i2 = 0, i3 = 0, i5 = 0;
  for (let i = 1; i < n; i++) {
    let x = Math.min(2 * seq[i2], 3 * seq[i3], 5 * seq[i5]);
    seq.push(x);
    if (2 * seq[i2] <= x) i2++;
    if (3 * seq[i3] <= x) i3++;
    if (5 * seq[i5] <= x) i5++;
  }

e-mihaylin

const quickSort = (arr, left, right) => {
  let len = arr.length, 
  pivot,
  partitionIndex;

  if (left < right){
    pivot = right;
    partitionIndex = partition(arr, pivot, left, right);
    
    //sort left and right