hooks-component

Addon used to experiment with React Hooks style APIs in Ember apps via existing public APIs.

Installation

ember install hooks-component

This addon provide 2 DIFFERENT - API's

• React way hooks implementation (always call component function on rerender).
• Ember way hooks implementation (call component function on first render only).

Usage in React-Way

The hooks-component API supports public React HooksAPI

Builtin hooks

• useEffect -> just like in React API
• useState -> just like in React API
• useLayoutEffect -> just like in React API

---

• getService -> getService(serviceName) -> service lookup hook
• getController -> getController(serviceName) -> controller lookup hook
• getRoute -> getRoute(routeName) -> route lookup hook
• getStore -> store service lookup
• getOwner -> getOwner() -> equals getOwner(this) in Ember.

Example

import { reactComponent, useEffect, useState } from "hooks-component";

function ConferenceSpeakersReact() {
	const [ speakers ] = useState(['Tom', 'Yehuda', 'Ed']);
	const [ current, updateCurrent ] = useState(0);

	useEffect(() => {
		console.log('dummy effect');
	});

	const next = () => {
		let nextSpeaker = current + 1;
		updateCurrent(nextSpeaker);
	}

	return {
		currentlySpeaking: speakers[current],
		moreSpeakers: (speakers.length - 1) > current,
		current,
		next, speakers
	}
}

export default reactComponent(ConferenceSpeakersReact);

{{!-- app/templates/components/conference-speakers-react.hbs --}}

<div>
  <p>Speaking: {{this.currentlySpeaking}}</p>
  <ul>
    {{#each speakers key="@index" as |speaker|}}
      <li>{{speaker}}</li>
    {{/each}}
  </ul>

  {{#if this.moreSpeakers}}
    <button onclick={{action this.next this.current}}>Next</button>
  {{else}}
    <p>All finished!</p>
  {{/if}}
</div>

How to create custom hooks?

• getContextId -> getContextId() -> get current instance context id (same between rerenders)
• getRerender -> return binded to current instance update function
• addBeforeCallTask -> execute some callback before component update
• addBeforeDestroyTask -> execute some callback before any component destroy

// utils/custom-hook.js

import { getContextId, getRerender, addBeforeCallTask, addBeforeDestroyTask } from  "hooks-component";

const DUMMY_STORE = {};
var CALL_COUNTER = 0;

addBeforeCallTask(()=>{
	CALL_COUNTER = 0;
});

addBeforeDestroyTask(()=>{
	const uid = getContextId();
	if (uid in DUMMY_STORE) {
		delete DUMMY_STORE[uid];
	}
});

export function myCustomHook(componentStoreDefaultValue = {}) {
	const uid = getContextId(); // current component instance ID
	const hookCallId = CALL_COUNTER; // how many times hook called during rendering
	if (!(uid in DUMMY_STORE)) {
		DUMMY_STORE[uid] =  {}; // init store for component instance;
	}
	if (!(hookCallId in DUMMY_STORE[uid])) {
		// init store for exact call number inside component isntance;
		DUMMY_STORE[uid][hookCallId] = componentStoreDefaultValue;
	}
	// get current instance + callNumber state
	let state = DUMMY_STORE[uid][hookCallId];
	// get rerender function (must be inside hook)
	let rerender = getRerender();
	// increment hook call counter
	CALL_COUNTER++;
	// return current state for exact component and callNumber and update state function
	return [ state, function(newState) {
		Object.assign(state, newState);
		// rerender will invoke component rerender
		rerender();
	}
}

import { reactComponent } from "hooks-component";
import myCustomHook from "utils/custom-hook";

function ConferenceSpeakersReact() {
	const [ state , patchState ] = myCustomHook({ keys: 1 });
	const [ fish, patchFish ] = myCustomHook({ salmon: 1 });
	const { keys } = state;
	const { salmon } = fish;

	const next = () => {
		patchState({
			keys: keys + 1
		})
	}

	const addSalmon = () => {
		patchFish({
			salmon: salmon + 1
		})
	}

	return { keys, next, salmon }
}

export default reactComponent(ConferenceSpeakersReact);

---

Usage in Ember-Way

The hooks-component API supports part of React hooks API, including:

updateContext - just like setProperties;
useEffect - do some calculation after dependent keys changed
extract - just like getWithDefault for component arguments

useEffect - inside component function context support: function, tracked property paths in array-like style ['foo.length', 'foo', 'foo.firstObject'];

All effects called during first render, on rerender effects called only if "tracked" property changed.

Example

// app/components/conference-speakers.js (.ts would also work)
import hookedComponent from "hooks-component";

function ConferenceSpeakers(attrs = {}) {

	const { updateContext, useEffect, extract } = this;

	useEffect(({current, speakers}) => {
		updateContext({
			currentlySpeaking: speakers[current],
			moreSpeakers: (speakers.length - 1) > current
		})
	}, ['current'] );

	const next = (current) => {
		current++;
		updateContext({
			current 
		});
	}

	return extract(attrs, {
		next,
		current: 0,
		speakers: ['Tom', 'Yehuda', 'Ed']
	});
}

export default hookedComponent(ConferenceSpeakers);

{{!-- app/templates/components/conference-speakers.hbs --}}

<div>
  <p>Speaking: {{currentlySpeaking}}</p>
  <ul>
    {{#each speakers key="@index" as |speaker|}}
      <li>{{speaker}}</li>
    {{/each}}
  </ul>

  {{#if moreSpeakers}}
    <button onclick={{action next this.current}}>Next</button>
  {{else}}
    <p>All finished!</p>
  {{/if}}
</div>

useEffect API

function shouldRecomputeEffect(oldObject: object, newObject: object): boolean;
type Tracker = string | object | shouldRecomputeEffect;
type cleanupComputedEffect = undefined | Function;
function computeEffect(newContext: any): cleanupComputedEffect;

function useEffect(computeEffect, trakedItems?: Tracker | Tracker[] , useTrackersOnFirstRender?: boolean = false)

How it's working?

Current hookedComponents implementation logic:

• We run component function only once, in component creation time.
• component function accept named params (args) as first argument, and return context object.
• updateContext method invoke existing effects and then, do setProperties(currentContext, updatedProps).
• if component args updated, it invokes updateContext method with updated args.
• useEffect method adds "after updateContext and before setProperties callbacks with updatedProps object as argument";
• if useEffect call return function, it will be called before this effect call next time.
• updateContext inside useEffect don't reinvoke effects, just patching updatedProps with new data.

Contributing

Installation

• git clone <repository-url>
• cd hooks-component
• yarn install

Linting

• yarn lint:js
• yarn lint:js --fix

Running tests

• ember test – Runs the test suite on the current Ember version
• ember test --server – Runs the test suite in "watch mode"
• ember try:each – Runs the test suite against multiple Ember versions

Running the dummy application

• ember serve
• Visit the dummy application at http://localhost:4200.

For more information on using ember-cli, visit https://ember-cli.com/.

License

This project is licensed under the MIT License.