Function use_default

pub fn use_default<'hook, T, F>(
    init_fn: F,
    default: T,
) -> impl 'hook + Hook<Output = UseDefaultHandle<T>>
where
    T: 'static + 'hook,
    F: FnOnce() -> Option<T> + 'hook,

A state hook that returns the default value when state is None.

Example

use yew_hooks::prelude::*;

#[function_component(UseDefault)]
fn default() -> Html {
    let state = use_default(|| None, "Hello(default)".to_string());

    let onclick = {
        let state = state.clone();
        Callback::from(move |_| {
            state.set(Some("World!".to_string()));
        })
    };

    let onclear = {
        let state = state.clone();
        Callback::from(move |_| {
            state.set(None);
        })
    };
    
    html! {
        <>
            <button {onclick}>{ "Set to World!" }</button>
            <button onclick={onclear}>{ "Clear" }</button>
            <b>{ "Current value: " }</b>
            { &*state }
        </>
    }
}

Note

When used in function components and hooks, this hook is equivalent to:

pub fn use_default<T, F>(init_fn: F, default: T) -> UseDefaultHandle<T>
where
    T: 'static,
    F: FnOnce() -> Option<T>,
{
    /* implementation omitted */
}