BAMBOO DISCO

function disco() {

  function randomElement(arr) {
    return arr[Math.floor(Math.random() * (arr.length - 1))];
  }

  var blocks = Array.prototype.slice.call(document.querySelectorAll("#wallboard .build > .result"));
  var colours = ["pink", "blue", "white", "purple", "grey", "red", "yellow"];
  var randomBlock = randomElement(blocks)
  randomBlock.style.background = randomElement(colours);
}