var curIndex = 1 ;

function prev() {

if(curIndex == 1) return;

var curPage = document.getElementById("page" + curIndex);

curPage.style.webkitTransform = "rotateX(90deg)";

curIndex--;

var prevPage = document.getElementById("page" + curIndex);

prevPage.style.webkitTransform = "rotateX(0deg)";

}

function next() {

if(curIndex == 6) return;

var curPage = document.getElementById("page" + curIndex);

curPage.style.webkitTransform = "rotateX(-90deg)";

curIndex++;

var nextPage = document.getElementById("page" + curIndex);

nextPage.style.webkitTransform = "rotateX(0deg)";

}