Change url when manually scrolled to an anchor?

By Default, if I have anchors in my website, then the URL on the address bar is changed, when I click on a link (ie. www.mysite.com/#anchor)

Is it possible to change the URL in the address bar instantly when I scroll to an anchor? Or have a long document with multiple anchors and the url changes on address bar, when I hit a new anchor?

Solution 1:

Try using this jquery plugin: Scrollorama. It has tons of cool features and you can use window.location.hash to update your browsers hash.

Alternatively, you can add a "scroll" event to check when an anchor is reached.

Here is a working fiddle to illustrate the event: http://jsfiddle.net/gugahoi/2ZjWP/8/ Example:

$(function () {
    var currentHash = "#initial_hash"
    $(document).scroll(function () {
        $('.anchor_tags').each(function () {
            var top = window.pageYOffset;
            var distance = top - $(this).offset().top;
            var hash = $(this).attr('href');
            // 30 is an arbitrary padding choice, 
            // if you want a precise check then use distance===0
            if (distance < 30 && distance > -30 && currentHash != hash) {
                window.location.hash = (hash);
                currentHash = hash;
            }
        });
    });
});

Solution 2:

you can use HTML 5 pushstate to change the URL in the address bar

window.history.pushstate

1. https://developer.mozilla.org/en-US/docs/DOM/Manipulating_the_browser_history
2. How can I use window.history.pushState 'safely'

Solution 3:

1. Bind a handler to jquery scroll event.
2. Check if an anchor is currently visible on-screen with this jquery script.
3. Use pushstate or set location (probably will cause jumps)

Solution 4:

You can bind to the jQuery scroll event (http://api.jquery.com/scroll/) and on each call of the callback called, check how far on the document the user has scrolled by checking this value: .scrollTop (http://api.jquery.com/scrollTop/) and set the anchor by manipulating te location.hash object (http://www.w3schools.com/jsref/prop_loc_hash.asp).

It would be something like this:

// Checks if the passed element is visible on the screen after scrolling
// source: http://stackoverflow.com/questions/487073/check-if-element-is-visible-after-scrolling
function isScrolledIntoView(elem) {
  var docViewTop = $(window).scrollTop();
  var docViewBottom = docViewTop + $(window).height();

  var elemTop = $(elem).offset().top;
  var elemBottom = elemTop + $(elem).height();

  return ((elemBottom <= docViewBottom) && (elemTop >= docViewTop));
}

$('#document').scroll(function(e) {
  var anchors = $('.anchor');
  for (var i = 0; i < anchors.length; ++i) {
    if (isScrolledIntoView(anchors[i])){
      var href = $(anchors[i]).attr('href');
      location.hash = href.slice(href.indexOf('#') + 1);
      break;
    }
  }
});

You could be more precise, if you sort the anchors after selecting them, so that the first visible anchor will be set always.