function preLoad() {
  var onImages = new Array();
  var field;

  // グローバルナビ用画像先読み
  for (field in gPreLoadList) {
    onImages[field] = new Image();
    onImages[field].src = gPreLoadList[field];
  }
  // カテゴリ別画像先読み
  for (field in mPreLoadList) {
    onImages[field] = new Image();
    onImages[field].src = mPreLoadList[field];
  }
  gAction = "true";
}

function changeImage(imageName, fileName) {
  if (gAction == "true") {
    document.images[imageName].src = fileName;
  }
}

/* <input type="image">の画像切り替え用 */
function changeSource(elemID, fileName) {
  document.getElementById(elemID).setAttribute("src", fileName);
}