Debounce helper spike

helpers::debounce.js

import { helper } from '@ember/component/helper';
import { isDestroyed } from '@ember/destroyable';
import { buildWaiter } from '@ember/test-waiters';

const testWaiter = buildWaiter('debounce-helper');
// WeakMap<Function, { timeoutId, asyncToken }>();
const TIMERS = new WeakMap();

function debounceHelper([context, action], { timeout }) {
	return function(...args) {
		if (TIMERS.has(action)) {
			const { timeoutId, asyncToken } = TIMERS.get(action);
			clearTimeout(timeoutId);
			testWaiter.endAsync(asyncToken);
		}

		const asyncToken = testWaiter.beginAsync();
		const timeoutId = setTimeout(() => {
			if (isDestroyed(context)) {
				testWaiter.endAsync(asyncToken);
				return;
			}
			try {
				action.call(context, ...args);
			}
			finally {
				testWaiter.endAsync(asyncToken);
			}
		}, timeout);

		TIMERS.set(
			action, { timeoutId, asyncToken },
		);
	};
}

export default helper(debounceHelper);

tests::integration::helpers::debounce-test.js

import { module, test } from 'qunit';
import { setupRenderingTest } from 'ember-qunit';
import { render, click, settled, typeIn } from '@ember/test-helpers';
import { hbs } from 'ember-cli-htmlbars';

module('Integration | Helper | debounce', function(hooks) {
	setupRenderingTest(hooks);

	test('Debounces the action calls', async function(assert) {
		this.set('actionToCall', function() {
			assert.step('clicked');
		});

		await render(hbs`
      {{!-- template-lint-disable data-qid-interactive --}}
      <button type="button"
				{{on 'click' (debounce this this.actionToCall timeout=100)}}
			>Click Me</button>
		`);

		// Don't wait here, we want to click a bunch and wait for settled later
		click('button');
		click('button');
		click('button');
		click('button');
		await settled();
		assert.verifySteps(['clicked']);
	});

	test('Doesnt error when the context is gone', async function(assert) {
		this.set('actionToCall', function() {
			assert.step('clicked');
		});

		await render(hbs`
			{{!-- template-lint-disable data-qid-interactive --}}
      <button type="button"
				{{on 'click' (debounce this this.actionToCall timeout=100)}}
			>Click Me</button>
		`);

		click('button'); // Don't wait because we want the test to finish
		assert.verifySteps([]);
	});

	test('Works on an input as well', async function(assert) {
		this.set('value', null);
		this.set('setValue', function(value) {
			assert.step(value);
			this.set('value', value);
		});

		await render(hbs`
      {{!-- template-lint-disable require-input-label --}}
      <input
				data-qid-input
				value={{this.value}}
				{{on 'keyup' (pick 'target.value' (debounce this this.setValue timeout=100))}}
			/>
		`);

		await typeIn('[data-qid-input]', 'farm');
		assert.verifySteps(['farm']);
		assert.equal(this.value, 'farm');
	});
});