Create Event Hook

Creates a hook that can be used to create event listeners. Useful for creating functions that need to be called on a specific event. With that you can build reusable functions.

🎬 Usage

<script>
    import { create_event_hook } from '@sveu/shared'

    function request(url) {
        const fetch_result = create_event_hook()

        const fetch_error = create_event_hook()

        fetch(url)
            .then(result => fetch_result.trigger(result))
            .catch(error => fetch_error.trigger(error?.message))

        return {
            on_result: fetch_result.on,
            on_error: fetch_error.on,
        }
    }
</script>

👩‍💻API

↩️ Returns

Name	Description	Type
on	Add a function to the event hook	`(fn: (param: T) => void): {off: () => void;}`
off	Remove a function from the event hook	`(fn: (param: T) => void): void`
trigger	Trigger the event hook	`(param: T): Promise<void[]>`

🧪 Playground

Source Code 👀

Source Code

import { on_destroy } from "../on_destroy"
import type { EventHook } from "../utils"

/**
 * Utility for creating event hooks
 *
 * @returns - Event hooks
 * - `on` - Add a function to the event hook
 * - `off` - Remove a function from the event hook
 * - `trigger` - Trigger the event hook
 */
export function create_event_hook<T = any>(): EventHook<T> {
    const fns: Set<(param: T) => void> = new Set()

    /**
     * Remove a function from the event hook
     *
     * @param fn - Function to remove
     */
    function off(fn: (param: T) => void) {
        fns.delete(fn)
    }

    /**
     * Add a function to the event hook
     *
     * @param fn - Function to add
     *
     * @returns - Function to remove the function
     */
    function on(fn: (param: T) => void) {
        fns.add(fn)

        const off_fn = () => off(fn)

        on_destroy(off_fn)

        return {
            off: off_fn,
        }
    }

    /**
     * Trigger the event hook
     *
     * @param param - Parameter to pass to the functions
     *
     * @returns - Promise that resolves when all functions have resolved
     */
    function trigger(param: T) {
        return Promise.all(Array.from(fns).map((fn) => fn(param)))
    }

    return {
        on,
        off,
        trigger,
    }
}

Last update: 2023-03-10

Authors: Mohamed-Kaizen