lavalamp.js

A replacement for infinite scroll. Works both ways (next and previous).

Demo

HTML structure

• a.button#previous = Load previous
• your page content
• a.button#next = Load next
• a#lavalamp including a span = Loading

How it works

There are 2 buttons: #previous and #next, that encapsulate the page.

When either of them is clicked, the #lavalamp HTML element covers the whole viewport while both the content of the page and the scroll position are updated.

Because all 3 elements look the same, it looks like the button clicked is expanding to cover the page.

For example, if you click next:

• the lavalamp is displayed, and initially positioned on top of the next button
• the lavalamp's bottom and height properties are animated through CSS to cover the whole page
• scrolling is temporarily disabled
• the page scrolls to the top
• when the new content is loaded, the lavalamp is animated upwards to match the previous button
• the lavalamp is hidden and reset, scrolling is re-enabled

Additional details

• For the sake of the demo, I use a setTimeout to simulate an Ajax call (the content remains unchanged).
• I also use a timeout after the last animation. I could use to detect CSS animation ends, but a timeout provides more flexibility, and prevents having to deal with browser inconsistencies. Plus, it's only 1 line.
• The previous button is the first child, the next button is the last child. It's possible to have other elements before and/or after, but then the illusion of the clicked button expanding is harder to execute because the lavalamp needs to be positioned exactly on the clicked button (which in the case, would not be exactly at top: 0; or bottom: 0;). It's possible to change the CSS animation values if needed though.
• The viewport is the whole body. It's possible to have a fixed header and/or footer as well, because the lavalamp is fixed as well. So, if you have a header that's 70px high, just change the CSS animation's top values to be 70px, not 0; (GIF demo coming soon).

Is this production-ready?

Kind of. The CSS animations should work well. The JS only takes care of updating the CSS classes, showing/hiding the lavalamp, and scrolling up and down. But it can be improved.

This repo is just a demo to showcase the intended user experience. Feel free to implement as you wish.

License

The MIT License (MIT)

Copyright (c) 2014 Jeremy Thomas

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.