Not exactly what you’re saying, but a bit closer. With this library you set what css classes on the page are “hot”, it fetches the next page state and replaces

Not exactly what you’re saying, but a bit closer. With this library you set what css classes on the page are “hot”, it fetches the next page state and replaces that part of the page with the new state: https://github.com/robrohan/diffy https://github.com/robrohan/diffy