[alvarlagerlof]

JavaScript simply shouldn't handle a lot of layout. It's not running in sync with the layout engine in css.

[Sesse__]

There has been some movement to handle CSS layout in JavaScript (running in a service worker, so that it cannot have state, but otherwise fully in sync with the layout), as part of the “Houdini” effort: https://www.w3.org/TR/css-layout-api-1/

(Disclosure: I work on the style team in Chromium)