At the moment the functionality of the browser's back button has been restored, and the visitor can see the bookmarkable URL in the address bar.
If the page is requested with a hash fragment in it, the page will automatically jump to the specified <section> when the page loads. In this part we'll add some code that checks the hash property of the document.location object and if a hash is detected, it will scroll to the corresponding part of the page smoothly.
To enable this, we should add the following code directly after where we define our starting variables near the top of the script file, and directly before where we listen for the scroll event:
if (document.location.hash) {
var href = document.location.hash,
target = parseInt(href.split("#part")[1]),
targetOffset = sections.eq(target - 1).offset().top;
page.scrollTop(0);
document.location.hash = "";
scrollPage(href, targetOffset, true);
}