An interesting brief here, from an independent property agent. They wanted a ‘price savings comparison slider’ for WordPress.

We got the mathematics nailed down in Javascript, kitted it out with nudge buttons (including ‘hold-down’, as an extra usability feature), and coded special measures to get it behaving responsively, and on all ‘touch-based’ devices.

We were pretty proud of the final WordPress Plugin (also implementable as a Widget or a shortcode); it was very small & had an absolutely negligible effect on performance (Approximately 60mS to load on the front end).