Load content without redirecting page using window.history.pushState

I have css animation for preloader.

I need help to update content smoothly without redirecting page, using following functions

$(window).on("popstate", function() { });

window.history.pushState({path: ""},"","");

Update link & content of next page after preloader progressbar animation ends webkitTransitionEnd without redirecting to page.

Need help to complete following functions

function changeUrl() { }
function updateContent() { }

Html/CSS/Js code (jsfiddle links)

after adding 'loading' class to body tag (Full Window)
after removing 'loading' class from body tag (Full Window)