[kleigenfreude]

Some computers are too old and slow to run the JS in the client as the IDE. Either the browser is old and incompatible, or it would just waste precious internet cafe/library computer time for each action.

Either the JS needs to be fast and compliant with much older browsers, or you just do a webform with old HTML tables as structure and so everything server-side.

Then you have the opposite problem in that those with newer computers wouldn't want to use it. So you might have to provide multiple levels of support, similar to how Gmail and OWA have a light client and a heavy client.