Javascript/戻り値

function sample1Func(){
  function add(a, b){
	var result = a + b;
	return result;
}

  var result1 = add(5, 4);
  console.log(result1);

  var result2 = add(20, 4)
  console.log(result2);

  var result3 = add(result1, result2);
  console.log(result3);
}
	

var s2Array = [
	"../img/1.jpg", "../img/2.jpg", "../img/3.jpg",
	"../img/4.jpg", "../img/5.jpg", "../img/6.jpg"
];
function s2Rnd(){
  return Math.floor(Math.random()*s2Array.length);
}
function s2Func(){
  var s2Div = document.getElementById("s2Div");
  s2Div.innerHTML = "";
  var s2Img = document.createElement("img");
  s2Img.style.width = "200px";
  s2Img.src = s2Array[s2Rnd()];
  s2Div.appendChild(s2Img);
}