Modification d'un script d'onglets jQuery

  window.onload=function() {   

      // get tab container   
      var container = document.getElementById("tabContainer");   
        // set current tab   
        var navitem = container.querySelector(".tabs ul li");   
        //store which tab we are on   
        var ident = navitem.id.split("_")[1];   
        navitem.parentNode.setAttribute("data-current",ident);   
        //set current tab with class of activetabheader   
        navitem.setAttribute("class","tabActiveHeader");   

        //hide two tab contents we don't need   
        var pages = container.querySelectorAll(".tabpage");   
        for (var i = 1; i < pages.length; i++) {   
          pages[i].style.display="none";   
        }   

        //this adds click event to tabs   
        var tabs = container.querySelectorAll(".tabs ul li");   
        for (var i = 0; i < tabs.length; i++) {   
          tabs[i].onclick=displayPage;   
        }   
    }   

    // on click of one of tabs   
    function displayPage() {   
      var current = this.parentNode.getAttribute("data-current");   
      //remove class of activetabheader and hide old contents   
      document.getElementById("tabHeader_" + current).removeAttribute("class");   
      document.getElementById("tabpage_" + current).style.display="none";   

      var ident = this.id.split("_")[1];   
      //add class of activetabheader to new active tab and show contents   
      this.setAttribute("class","tabActiveHeader");   
      document.getElementById("tabpage_" + ident).style.display="block";   
      this.parentNode.setAttribute("data-current",ident);   
    } 

  <div id="tabContainer">   
    <div class="tabs">   
      <ul>   
        <li id="tabHeader_1">Onglet 1</li>   
        <li id="tabHeader_2">Onglet 2</li>   
        <li id="tabHeader_3">Onglet 3</li>   
      </ul>   
    </div>   
    <div id="tabscontent">   
    <div class="tabpage" id="tabpage_1">   
    [Contenu]   
    </div>   
    <div class="tabpage" id="tabpage_2">   
    [Contenu]   
    </div>   
    <div class="tabpage" id="tabpage_3">   
    [Contenu]   
    </div>   
    </div>
    </div>
 

_____Shaka_____   
 Memento Mori