Header parallax using Intersection Observer

Demo

https://handsomemedia.github.io/Header-Parallax-Int-Observer/dist/

Notes

• uses native Intersection Observer API
• more performant than listening to scroll event
• less voodoo involved than CSS perspective method
• requires a "sentinel" element added to the DOM
• currently requires an Intersection Observer polyfill for Safari (not implemented here)
• https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
• https://github.com/w3c/IntersectionObserver/tree/master/polyfill
• https://developers.google.com/web/updates/2016/04/intersectionobserver