From 4c2b9603a12c7e9cd138cb7eb934f41095936b6d Mon Sep 17 00:00:00 2001
From: Jacob Wright <jacwright@gmail.com>
Date: Sat, 25 Aug 2018 13:39:48 -0600
Subject: [PATCH] Fix for each-blocks preventing outros from completing

Unkeyed each blocks end up with trailing `null` values that prevent the whole from being outroed. This fixes it so the null values are removed before outroing the remaining blocks.

Fixes #1617
---
 src/compile/nodes/EachBlock.ts                |  1 +
 .../transition-js-each-block-outro/_config.js |  3 ++
 .../_config.js                                | 29 +++++++++++++++++++
 .../main.html                                 | 20 +++++++++++++
 4 files changed, 53 insertions(+)
 create mode 100644 test/runtime/samples/transition-js-nested-each-delete/_config.js
 create mode 100644 test/runtime/samples/transition-js-nested-each-delete/main.html

diff --git a/src/compile/nodes/EachBlock.ts b/src/compile/nodes/EachBlock.ts
index cae0aa7352..bb726982df 100644
--- a/src/compile/nodes/EachBlock.ts
+++ b/src/compile/nodes/EachBlock.ts
@@ -480,6 +480,7 @@ export default class EachBlock extends Node {
 		if (outroBlock && this.compiler.options.nestedTransitions) {
 			const countdown = block.getUniqueName('countdown');
 			block.builders.outro.addBlock(deindent`
+				${iterations} = ${iterations}.filter(Boolean);
 				const ${countdown} = @callAfter(#outrocallback, ${iterations}.length);
 				for (let #i = 0; #i < ${iterations}.length; #i += 1) ${outroBlock}(#i, 0, ${countdown});`
 			);
diff --git a/test/runtime/samples/transition-js-each-block-outro/_config.js b/test/runtime/samples/transition-js-each-block-outro/_config.js
index 5e8b99d88d..0ce6573082 100644
--- a/test/runtime/samples/transition-js-each-block-outro/_config.js
+++ b/test/runtime/samples/transition-js-each-block-outro/_config.js
@@ -12,5 +12,8 @@ export default {
 		assert.equal( divs[0].foo, undefined );
 		assert.equal( divs[1].foo, 0.5 );
 		assert.equal( divs[2].foo, 0.5 );
+
+		raf.tick( 100 );
+		assert.htmlEqual(target.innerHTML, '<div>a</div>');
 	}
 };
\ No newline at end of file
diff --git a/test/runtime/samples/transition-js-nested-each-delete/_config.js b/test/runtime/samples/transition-js-nested-each-delete/_config.js
new file mode 100644
index 0000000000..870f90efc4
--- /dev/null
+++ b/test/runtime/samples/transition-js-nested-each-delete/_config.js
@@ -0,0 +1,29 @@
+export default {
+	nestedTransitions: true,
+	skipIntroByDefault: true,
+
+	data: {
+		visible: true,
+		things: [ 'a', 'b', 'c' ]
+	},
+
+	test ( assert, component, target, window, raf ) {
+		assert.htmlEqual(target.innerHTML, `
+			<div>a</div>
+			<div>b</div>
+			<div>c</div>
+		`);
+
+		component.set({ things: [ 'a' ] });
+
+		raf.tick( 100 );
+		assert.htmlEqual(target.innerHTML, `
+			<div>a</div>
+		`);
+
+		component.set({ visible: false });
+
+		raf.tick( 200 );
+		assert.htmlEqual(target.innerHTML, '');
+	}
+};
diff --git a/test/runtime/samples/transition-js-nested-each-delete/main.html b/test/runtime/samples/transition-js-nested-each-delete/main.html
new file mode 100644
index 0000000000..e12370703e
--- /dev/null
+++ b/test/runtime/samples/transition-js-nested-each-delete/main.html
@@ -0,0 +1,20 @@
+{#if visible}
+	{#each things as thing}
+		<div transition:foo>{thing}</div>
+	{/each}
+{/if}
+
+<script>
+	export default {
+		transitions: {
+			foo(node, params) {
+				return {
+					duration: 100,
+					tick: t => {
+						node.foo = t;
+					}
+				};
+			}
+		}
+	};
+</script>