How to handle onsubmit with Domina

Question

I've been trying to write an equivalent for the following in cljs using the Domina library:

HTML:

<form id="my-form">
    <input type="text />
    <input type="submit" />
</form>

Javascript (jQuery):

$("#my-form").submit(function() {
    console.log("submit suppressed");
    return false;
});

A solution not to my satisfaction (without Domina library which is very verbose):

(set! (.-onsubmit (.getElementById js/document "my-form")) #(do
                                                              (.log js/console "submit suppressed")
                                                              false))

I've tried many solutions which all failed - all somewhat similar to:

(listen! (by-id "my-form") :submit #(do
                                      (log "submit suppressed")
                                      false))

It is on purpose that I don't use the click event, because I also want the function to be executed when the form is submitted by code or keyboard.

Answer 1

When you return false from within a jQuery event handler, the library will automatically call e.preventDefault and e.stopPropagation (for more info see here). Calling this functions is the right way to control the behaviour of the event.

Domina wraps js/Event in something that ClojureScript understands. So you can call preventDefault and stopPropagation directly, without using the Javascript interop. You can read more about this neat trick here: https://github.com/levand/domina#event-objects.

This trick is probably what is causing returning false to not work at all. The way this trick is implemented (take a look at the code here) is by wrapping your function with another function that always return true.

So your code should be more like this:

(listen! (by-id "my-form") :submit
         (fn [e]
           (do
             (log "submit suppressed")
             (prevent-default e)
             (stop-propagation e))))