window.onload=function() {
tab.setup = { 
tabs: document.getElementById('tab').getElementsByTagName('li'), 
  
pages: [ 
document.getElementById('page1'), 
document.getElementById('page2'), 
document.getElementById('page3'), 
document.getElementById('page4')
] 
} //オブジェクトをセット 
tab.init(); //起動！ 

}


var tab = { 
init: function(){ 
var tabs = this.setup.tabs; 
var pages = this.setup.pages; 
  
for(i=0; i<pages.length; i++) { 
if(i !== 0) pages[i].style.display = 'none'; 
tabs[i].onclick = function(){ tab.showpage(this); return false; }; 
} 
}, 
  
showpage: function(obj){ 
var tabs = this.setup.tabs; 
var pages = this.setup.pages; 
var num; 
  
for(num=0; num<tabs.length; num++) { 
if(tabs[num] === obj) break; 
} 
  
for(var i=0; i<pages.length; i++) { 
if(i == num) { 
pages[num].style.display = 'block'; 
tabs[num].className = 'present'; 
} 
else{ 
pages[i].style.display = 'none'; 
tabs[i].className = null; 
} 
} 
} 
}