text: combination_arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'A', 'B', 'C', 'D', 'E', 'F'];
  
  var button = document.querySelector('.button');
  var background_color = document.querySelector('body');
  var hexcode = document.getElementById('hexcode');
  
  background_color.style.backgroundColor = "rgba(70, 70, 70)";
  button.addEventListener('click',work);
  
  function work(){
      let col = '#';
  
      for (let i = 0; i < 6; i++)
      {
          let random = Math.floor(Math.random() * 16);    // int( num b/w 0 and 1 *10))
          col += combination_arr[random];
      }
  
      background_color.style.backgroundColor = col; 
      hexcode.innerHTML = col;
  }