That can work for simple use cases, but most of the time there are Specific validation conditions. For example the password should contain lowercase, uppercase letters numbers and should not contain special characters (like ?*%). This example can surely be done with built in HTML valodators, but the aim is to get an idea how you can do more advanced validations.
Okay lets get into a specific use case I faced a few years earlier. On a registration site we had to validate if an email address is a real existing address. To do that we had to call an API to validate the email address. There’s no way to do that eith built in html.
Similarly, any JS-only validation can be bypassed (breakpoints, changing values etc.)
Far too many sites these days forget this. I've lost count of the number of forms I've 'fooled' into letting me continue as all the validation is done client-side. I've even seen 'server-side' validation fail as the result of a server-side check whose result was being checked on the client-side - something like this:
constformIsValid=validateFormServerSide()// make a breakpoint here, change formIsValid to true ...// Voila! 'server-side' validation bypassedif(formIsValid){// Do stuff}
Thanks, Adam. This is exactly what I was looking for. A simple JavaScript validation that teaches me the basics of how to do this in a static way with JS, not an elaborate program with all the bells and whistles. And thanks for pointing out the backend validation too, I may have let that slip by without thinking all the way through how people can evade the front end pretty easily.
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That can work for simple use cases, but most of the time there are Specific validation conditions. For example the password should contain lowercase, uppercase letters numbers and should not contain special characters (like ?*%). This example can surely be done with built in HTML valodators, but the aim is to get an idea how you can do more advanced validations.
Your password example can be done with built-in validation
Okay lets get into a specific use case I faced a few years earlier. On a registration site we had to validate if an email address is a real existing address. To do that we had to call an API to validate the email address. There’s no way to do that eith built in html.
All the in-built stuff can be called with JS. You just need to augment it a little for cases like this - not re-invent the wheel
When a user use inspect element and change the pattern or and the type the build in validation would result in a false isValid
Similarly, any JS-only validation can be bypassed (breakpoints, changing values etc.)
Far too many sites these days forget this. I've lost count of the number of forms I've 'fooled' into letting me continue as all the validation is done client-side. I've even seen 'server-side' validation fail as the result of a server-side check whose result was being checked on the client-side - something like this:
True submitting a form needs also to be validate on server side.
Thanks, Adam. This is exactly what I was looking for. A simple JavaScript validation that teaches me the basics of how to do this in a static way with JS, not an elaborate program with all the bells and whistles. And thanks for pointing out the backend validation too, I may have let that slip by without thinking all the way through how people can evade the front end pretty easily.