leptos-rs/leptos · error

incorrect element type

Error message

incorrect element type

What it means

After obtaining the event target Element, event_target casts it to the requested type T via T::cast_from and panics with 'incorrect element type' when the target isn't of type T. The library throws it because the caller statically requested a specific element type the runtime event didn't produce.

Source

Thrown at tachys/src/renderer/dom.rs:364

                    ),
                    &el,
                    "removeEventListener"
                )
            });
            move || cb()
        })
    }

    pub fn event_target<T>(ev: &Event) -> T
    where
        T: CastFrom<Element>,
    {
        let el = ev
            .unchecked_ref::<web_sys::Event>()
            .target()
            .expect("event.target not found")
            .unchecked_into::<Element>();
        T::cast_from(el).expect("incorrect element type")
    }

    pub fn add_event_listener_delegated(
        el: &Element,
        name: Cow<'static, str>,
        delegation_key: Cow<'static, str>,
        cb: Box<dyn FnMut(Event)>,
    ) -> RemoveEventHandler<Element> {
        let cb = Closure::wrap(cb);
        let key = intern(&delegation_key);
        or_debug!(
            js_sys::Reflect::set(el, &JsValue::from_str(key), cb.as_ref()),
            el,
            "set property"
        );

        GLOBAL_EVENTS.with_borrow_mut(|events| {
            if !events.contains(&name) {

View on GitHub (pinned to 32d20f6c9d)

Solutions

1. Verify the requested type matches the element the listener is attached to (and delegation assumptions)
2. Check ev.target() manually and cast with T::cast_from, handling None instead of panicking
3. Prefer ev.current_target()/current_target_element when you want the element the listener was registered on
4. Scope delegated handlers so only expected child element types can trigger them

Example fix

// before
let btn: HtmlButtonElement = renderer.event_target(&ev); // panics if target is <svg>
// after
let t = ev.current_target().expect("listener element");
let btn = HtmlButtonElement::cast_from(t.unchecked_into());
if btn.is_none() { return; } // ignore unexpected targets

fn target_matches<T: CastFrom<Element>>(ev: &web_sys::Event) -> Option<T> {
    ev.target().and_then(|t| T::cast_from(t.unchecked_into::<Element>()))
}

// use the guard instead of the panicking helper:
if let Some(el) = target_matches::<MyEl>(&ev) { /* handle */ }
// else: ignore or handle unexpected target type

When it happens

Trigger: Calling event_target::<T> with a T that doesn't match the actual target, e.g. handler on a parent (delegated listener) where the clicked child is a different tag; button handler receiving clicks on an embedded <svg> or <img>; using event_target inside a document-level listener.

Common situations: Event delegation where bubbling targets differ from the listened element; mixing typed handlers with delegated events; clicks landing on child nodes (text/icons) whose element type differs from the expected one.

Related errors

• event.target not found
• could not find parent element
• placeholder parent should be Element
• tried to remove a parentless node
• Executor::spawn called, but no global 'spawn' function is co

AI-assisted analysis of leptos-rs/leptos@32d20f6c9d (2026-09-01). Data as JSON: /api/errors/3575f8e4ec86e20b. Report an issue: GitHub.