window.onload = function() {
  
  var Width = document.documentElement.scrollWidth;
  var h2    = document.getElementById("article").getElementsByTagName("h2");
  var len   = h2.length;
  
  for (var i=0; i<len; i++){
    element = document.createElement("span");
    h2[i].appendChild(element);
  }
  
}

function roleOver(img){
  
  if (img.src.indexOf("_off") != -1){
    img.src = img.src.replace("_off", "_on");
  } else{
    img.src = img.src.replace("_on", "_off");
  }
  
}

function convertArea(num, obj){
  
  if (document.getElementById("test" + num + "-2").style.display == "block"){
    document.getElementById("test" + num + "-1").style.display = "block";
    document.getElementById("test" + num + "-2").style.display = "none";
    obj.value = "この部分の記法を見る";
  } else{
    document.getElementById("test" + num + "-1").style.display = "none";
    document.getElementById("test" + num + "-2").style.display = "block";
    obj.value = "この部分を元に戻す";
  }
  
}