I'm extremely new to node.js, and have years of experience in PHP, so my thinking about the issues below, might be tainted by my backed ways.
I'm currently using node set up with foundation CSS, and using their reveal modal windows to display most of my forms. I want to avoid re-displaying them upon submit, and instead, validate them on client side.
Basic user creation will have fields as per below:
Form my basic validation i can use require to validate the input,
input(type="text",name="user[email]",placeholder="@",required)
but I would also like the client to check if the email already exists after the user types it in, and whether the passwords are correct.
I've been reading about the validator module but from the documentation I read about it, I only understand how to validate the values after they've been posted. I've seen the express-form module as well, but It's no longer maintained, so I would rather avoid it.
Could someone point me in the right direction?
I don't have any experience with validator or express-form, and I am not sure you need them for what you are trying to achieve. Most of what you are trying to do will be client side work (e.g. jQuery Ajax calls to validate the data) That kind of client-side code should be pretty much the same regardless of whether you use a Node.js backend or a PHP backend.
Injecting the initial JavaScript in your Jade page should be pretty straightforward once you figure out the proper syntax to include JavaScript in a Jade page. The wiring of DOM events on the page to make Ajax calls (onClick, onTextChanged, et cetera) will be conceptually the same as if you were writing a plain HTML page.
In your Node.js server side you'll need a route to handle the request to validate if an e-mail address already exists and that code very likely will return JSON that you will use in your client side form to display the results of the validation to the user. But that should also be very similar to what you would have done with a PHP backend.