Equivalent of @solid-primitives/refs `mergeRefs` but for event listeners

[Tronikelis]

Describe The Problem To Be Solved

Hi, so when I am creating components almost always I need to pass some callbacks to onClick or anything else like that, but I want the user of the component to be able to pass onClick as well, so now I need to pass that event to splitProps, and don't forget to pass both onClick and onclick because both variants could be used by the component user and then finally check if it is a function and then call it with the same params.

Doing this everytime is a burden.

Suggest A Solution

How I think about solving the problem:

• the helper should integrate the splitProps function from solid, as you would always use splitProps to get the callbacks
• the helper should call both the camelcase and the lowercase versions of the event, so if I use onClick inside the component, it shouldnt matter if the user passes onClick or onclick to the component, both of these should get triggered
• fully type-safe, but I assume this is the default for all of the helper fns

My very rough first try at implementing this:

import { mergeProps, splitProps } from "solid-js";

type AnyFn = (...params: any) => any;

type ExtractFunction<T> = Extract<T, AnyFn>;

type WithCallback<T> = {
    [K in keyof T as ExtractFunction<T[K]> extends never ? never : K]?: ExtractFunction<T[K]>;
};

export default function splitPropsWithCallback<
    T extends Record<any, any>,
    K extends (keyof T)[],
    G extends WithCallback<T>,
>(props: T, split: K, callbacks: G) {
    const [local, others] = splitProps(props, split);

    const withCallback = () => {
        const keys = Object.keys(callbacks) as (keyof typeof callbacks)[];
        const final = {} as typeof callbacks;

        for (const key of keys) {
            const inner = callbacks[key];

            const combined = (...params: any[]) => {
                if (typeof props[key] === "function") {
                    // eslint-disable-next-line @typescript-eslint/no-unsafe-call
                    props[key](...params);
                }
                if (typeof props[key.toString().toLowerCase()] === "function") {
                    // eslint-disable-next-line @typescript-eslint/no-unsafe-call
                    props[key.toString().toLowerCase()](...params);
                }

                // eslint-disable-next-line @typescript-eslint/no-unsafe-call
                return inner?.(...params);
            };

            // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
            final[key] = combined as any;
        }

        return final;
    };

    const mergedOther = mergeProps(others, withCallback);

    return [local, mergedOther] as const;
}

usage: https://playground.solidjs.com/anonymous/96db2b0c-0846-47ed-86ef-0e275c4b24e7

[gabrielmfern]

love this idea +1, for one of my project I had to make a hacky mergeCallbacks for this sorta of stuff

I wonder if it makes sense that this goes into @solid-primitives/props as well, like the combineStyle

[Tronikelis]

what I am using right now is mergeRefs + createEventListener:

    const onInput = () => {
        if (local.value && context) {
            context.setSelected(local.value);
        }
    };
    createEventListener(() => ref, "input", onInput);

This way I don't worry about the consumer overriding my events, seems like a better solution than hacking around with very custom stuff

[thetarnav]

+1 to just adding a bit of custom logic when needed

if ("onClick" in props) props.onClick(e)
localOnClick(e)

And for doing that automatically for all props, combineProps should do the job. It handles combining lowercase/camelCase handlers as well.

But I like the idea of the mergeCallbacks helper. I think you could do the same with chain helper from utils

onClick={chain(
    e => console.log("click:", e),
    props.onClick,
)}

[Tronikelis]

@thetarnav oh wow, did not know about combineProps and chain, very useful

[gabrielmfern]

+1 to just adding a bit of custom logic when needed

I'd agree it's easier, but the problem with that is that you will have to override the handler types from ComponentProps if you do this, because its types allow for bound event handlers. Does chain handle those as well?

[thetarnav]

Good point @gabrielmfern, it does not.