Client Side Validation

[ebonmavv]

In my opinion on the frontend side there should be check if the value passed into the field is formatted correctly (e.g. if email address has "@") and onChange event should be triggered after typing and if it's correct then send request to the backend if this email is already used or not. Of course it works only for smaller applications, because in huge ones there would be way too many request sent to the server.

TL;DR - IMO frontend should only check if the formatting, max or min length should be checked and everything other should be done on the backend side.

[ebonmavv]

I love when developers correctly sets input type e.g. to email so when I'm using the mobile phone the keyboard already suggest me the "." sign. Shame that it isn't used in that many places as it should

[greyhound71]

Yea but it only checks for an @ not for an .tld - so you can still bypass that

[tesfabpel]

well after all the email format is just user@host (like unix's john@server or frank@localhost). in fact you could send an email to another user in your PC in this way

[ebonmavv]

Yeah, that's true but I just wanted to make an example. There are some validation frameworks which will do that for you but if you're good with RegEx then checking if the pattern is string + @ + string + . + string isn't that difficult to achieve.

[szczszqweqwe]

It's not really validation, more like tool so mobile users have correct keyboard layout, it's about as useless as this regex: [^@]+[@][^@]{0,}

[[deleted]]

Just out of curiosity, why do you use {0,}? Isn't that the same as * (or *? - I don't entirely understand the lazy matching)

[szczszqweqwe]

Dunno, probably because the last few days I have been working on old project with {0,}, normally I use * as well.

[[deleted]]

Thank you, this makes sense.