An Interactivity API block, two years on

A carousel converted from a bespoke script in 2024, revisited to see whether the conversion held.

  the store                1.2 KB, unchanged
  the runtime              shipped by core on any page
                           with an interactive block,
                           including from plugins we
                           do not control
  directive breaking
    changes                 none in two years
  the progressive
    enhancement             still works, and is
                           asserted by a browser test

the conversion has cost nothing since the day it was
done, which is the outcome you hope for and rarely
write down.

The runtime being loaded by somebody else’s plugin means the shared cost is already paid on most pages, which improves the arithmetic for every block still on a bespoke script. That is an argument for converting the rest and it depends on which plugins are installed, which is not a stable basis for a decision.