var images = {
  // 画像とジャンプ先の URL のペア
  url : [
    ['/extension/corp_eng/design/corp_eng/images/img_keyvisual01.jpg', '/eng', 'Nippon Chemical & Screw Co., Ltd.'],
    ['/extension/corp_eng/design/corp_eng/images/img_keyvisual02.jpg', '/eng/products/type_material/reny', 'Nippon Chemical & Screw Co., Ltd.'],
    ['/extension/corp_eng/design/corp_eng/images/img_keyvisual03.jpg', '/eng', 'Nippon Chemical & Screw Co., Ltd.'],
    ['/extension/corp_eng/design/corp_eng/images/img_keyvisual04.jpg', '/eng/products/type_material/pc', 'Nippon Chemical & Screw Co., Ltd.']
    ],

  // 順番のシャッフル
  shuffle : function() {
    for (i = this.url.length; i > 0; --i) {
      tmp = this.url[p = Math.floor(Math.random()*i)] ;
      this.url[p] = this.url[i-1] ;
      this.url[i-1] = tmp ;
    }
  },

  p : 0, // 表示画像のポインタ

  // 画像表示
  put : function() {
    if (this.p >= this.url.length) this.p = 0 ;
      return '<a href="'+this.url[this.p][1]+'"><img src="'+this.url[this.p][0]+'" alt="'+this.url[this.p++][2]+'" /></a>';
  }
};

onload = function() {
  images.shuffle() ;
  divs = document.getElementsByTagName('div') ;
  for (i = 0; i < divs.length; ++i) {
    if (divs[i].className != 'keyvisual') continue ; // class が「keyvisual」ではない div はスルー
    divs[i].innerHTML += images.put() ;
  }
}