Overscroll.js

A tiny javascript library, to capture the moments when you've scrolled more than the screen allows (osx/ios)... so we can sneak in some little easter eggs. Here's a live demo, and here's a video !

Instructions

Overscroll.js is a stand alone library (no jquery, or the likes) so usage is pretty straight forward. All styling of easter egg elements is up to the user, Overscroll.js only handles moving your elements onto/off the screen, when you are scrolling beyond the pages height.

HTML

There aren't any restrictions for the html overscroll can bind too, that said, you do need to position them (ideally off screen) yourself. Overscroll will handle their movement.

<!-- Any element works, really -->
<img class="easter-egg" src="./img/awesome-source.jpg" />

CSS

You'll need to position the element you want to slide in/out of the screen initially. Since overscroll edits the transform of your element, you should try to avoid using transforms on it too.

That said, your positioning doesn't need to be anything too complex. For example:

.easter-egg {
	/* Dimensions */
	width: 300px;
	height: 500px;
	
	/* Fixed position */
	position: fixed;
	left: 50%;
	top: 0px;

	/* Centered horizontally, and hidden above screen */
	margin-left: -150px;
	margin-top: -500px;
}

Above, the margin-top: -500px hides the element above the top of the screen, since overscroll will handle showing it when the there is overscroll in that direction.

JS

Overscroll.js is fairly straight forward when it comes to kicking it off, you'll need to create a new instance of overscroll (and include the script in the page), and then bind elements to it once they have been rendered. You can do this with document.querySelector.

<img class="easter-egg-element" src="./img/awesome-source.png" />

<script>
var overscroll = new Overscroll();
window.onload = function() {
	overscroll.bindElement(document.querySelector('.easter-egg-element'));
}
</script>

There are options, for when the easter egg is at the top, or bottom.

<img class="easter-egg-element top" src="./img/awesome-source.png" />
<img class="easter-egg-element bottom" src="./img/awesome-source.png" />

<script>
var overscroll = new Overscroll();
window.onload = function() {
	overscroll.bindElement(document.querySelector('.easter-egg-element.top'), 'top');
	overscroll.bindElement(document.querySelector('.easter-egg-element.bottom'), 'bottom');
}
</script>

And finally, a delta, to show how sensitive the scroll should be, when in the overscroll area... this makes it easier for people to find, but isn't really necessary.

<img class="easter-egg-element" src="./img/awesome-source.png" />

<script>
var overscroll = new Overscroll();
window.onload = function() {
	overscroll.bindElement(document.querySelector('.easter-egg-element'), 'top', 2);
}
</script>

Image/Example

Here's a couple of screenshots of Overscroll.js in action. You should really look at the demo though, to get a full feel for the interactions, or check out the video!

Overscroll on the bottom:

Overscroll on the top:

Browser support

Overscroll has been tested in the latest stable builds of Safari and Chrome. IE & Firefox don't really have the "overscroll" zones, so they won't work. Its just for fun... so not the end of the world ;)

License

The MIT License (MIT)

Copyright (C) 2017 ~ Tim Holman ~ timothy.w.holman@gmail.com