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Comment by simonbarker87 | Hacker News Reader

It was all normal JS code to handle a complicated form we have on a customer facing portal page. By moving to htmx I was able to rely on the server side to handle basically everything with only a small addition of code to what it was already doing.

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I'm qurious what that code was doing that could be just moved to the backend. Usually forms have some validation for a better experience with the final validation on the server. Did you get rid of that and just show an error if the submission failed?

Near enough yes but it was a nice helpful error message with the form fully populated as they left it - as far as it looks the user it’s client side validation as the service responds with just the correct html for the form and htmx swaps out the chunk of html.

Its like old school for validation back in the CodeIgniter days.

So the 500 lines removed was literally just removing functionality in the first place (you should always validate on both sides anyway).

Isn’t that moving code around, not deleting it?

Most likely that code already existed server-side and was duplicated client-side. It's what usually happens since frontend code can't enforce invariants.

Near enough exactly this

Could you elaborate on what you mean by "frontend code can't enforce invariants" ?

Frontend code can be easily bypassed or changed so you can't trust it to keep the state of your application in good condition. Nothing prevents me from picking the same username as someone else if there is no server-side code stopping it. Nothing prevents me from replying to a deleted comment if I don't check with the server.

That means that any validation that you do client-side you need to repeat server-side. Any business logic that you have client-side you also need to repeat server-side.

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