expose add_render_callback as afterFlush - fixes #1976

index.mjs

@@ -3,5 +3,6 @@ export {
 	onDestroy,
 	beforeUpdate,
 	afterUpdate,
+	add_render_callback as afterFlush,
 	createEventDispatcher
 } from './internal';

test/runtime/samples/lifecycle-after-flush/_config.js

@@ -0,0 +1,20 @@
+export default {
+	async test({ assert, component, target, window }) {
+		const button = target.querySelector('button');
+		const click = new window.MouseEvent('click');
+
+		await button.dispatchEvent(click);
+		assert.deepEqual(component.snapshots, [
+			'before 0',
+			'after 1'
+		]);
+
+		await button.dispatchEvent(click);
+		assert.deepEqual(component.snapshots, [
+			'before 0',
+			'after 1',
+			'before 1',
+			'after 2'
+		]);
+	}
+};

test/runtime/samples/lifecycle-after-flush/main.html

@@ -0,0 +1,19 @@
+<script>
+	import { afterFlush } from 'svelte';
+
+	export let snapshots = [];
+
+	let count = 0;
+	let button;
+
+	function click() {
+		count += 1;
+		snapshots.push(`before ${button.textContent}`);
+
+		afterFlush(() => {
+			snapshots.push(`after ${button.textContent}`);
+		});
+	}
+</script>
+
+<button bind:this={button} on:click={click}>{count}</button>