From f0bf1ef8d5814e36b4d556753cfe953755e329b4 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Sat, 28 Apr 2018 23:51:05 -0400
Subject: [PATCH] recalculate each block values lazily - fixes #1286

---
 src/compile/nodes/EachBlock.ts                              | 4 ++--
 test/js/samples/deconflict-builtins/expected-bundle.js      | 4 ++--
 test/js/samples/deconflict-builtins/expected.js             | 4 ++--
 test/js/samples/each-block-changed-check/expected-bundle.js | 4 ++--
 test/js/samples/each-block-changed-check/expected.js        | 4 ++--
 5 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/compile/nodes/EachBlock.ts b/src/compile/nodes/EachBlock.ts
index cb58b31411..f96b330064 100644
--- a/src/compile/nodes/EachBlock.ts
+++ b/src/compile/nodes/EachBlock.ts
@@ -443,9 +443,9 @@ export default class EachBlock extends Node {
 				`;
 
 			block.builders.update.addBlock(deindent`
-				var ${each_block_value} = ${snippet};
-
 				if (${condition}) {
+					${each_block_value} = ${snippet};
+
 					for (var #i = ${start}; #i < ${each_block_value}.${length}; #i += 1) {
 						var ${this.each_context} = @assign(@assign({}, ctx), {
 							${this.contextProps.join(',\n')}
diff --git a/test/js/samples/deconflict-builtins/expected-bundle.js b/test/js/samples/deconflict-builtins/expected-bundle.js
index 4bc21f60a6..b677e75e29 100644
--- a/test/js/samples/deconflict-builtins/expected-bundle.js
+++ b/test/js/samples/deconflict-builtins/expected-bundle.js
@@ -186,9 +186,9 @@ function create_main_fragment(component, ctx) {
 		},
 
 		p: function update(changed, ctx) {
-			var each_value = ctx.createElement;
-
 			if (changed.createElement) {
+				each_value = ctx.createElement;
+
 				for (var i = 0; i < each_value.length; i += 1) {
 					var each_context = assign(assign({}, ctx), {
 						each_value: each_value,
diff --git a/test/js/samples/deconflict-builtins/expected.js b/test/js/samples/deconflict-builtins/expected.js
index aa928967c4..ce7e2fa52f 100644
--- a/test/js/samples/deconflict-builtins/expected.js
+++ b/test/js/samples/deconflict-builtins/expected.js
@@ -34,9 +34,9 @@ function create_main_fragment(component, ctx) {
 		},
 
 		p: function update(changed, ctx) {
-			var each_value = ctx.createElement;
-
 			if (changed.createElement) {
+				each_value = ctx.createElement;
+
 				for (var i = 0; i < each_value.length; i += 1) {
 					var each_context = assign(assign({}, ctx), {
 						each_value: each_value,
diff --git a/test/js/samples/each-block-changed-check/expected-bundle.js b/test/js/samples/each-block-changed-check/expected-bundle.js
index 560c0514ae..f4d29ba84a 100644
--- a/test/js/samples/each-block-changed-check/expected-bundle.js
+++ b/test/js/samples/each-block-changed-check/expected-bundle.js
@@ -192,9 +192,9 @@ function create_main_fragment(component, ctx) {
 		},
 
 		p: function update(changed, ctx) {
-			var each_value = ctx.comments;
-
 			if (changed.comments || changed.elapsed || changed.time) {
+				each_value = ctx.comments;
+
 				for (var i = 0; i < each_value.length; i += 1) {
 					var each_context = assign(assign({}, ctx), {
 						each_value: each_value,
diff --git a/test/js/samples/each-block-changed-check/expected.js b/test/js/samples/each-block-changed-check/expected.js
index 6b15078c79..75dfc20a7d 100644
--- a/test/js/samples/each-block-changed-check/expected.js
+++ b/test/js/samples/each-block-changed-check/expected.js
@@ -38,9 +38,9 @@ function create_main_fragment(component, ctx) {
 		},
 
 		p: function update(changed, ctx) {
-			var each_value = ctx.comments;
-
 			if (changed.comments || changed.elapsed || changed.time) {
+				each_value = ctx.comments;
+
 				for (var i = 0; i < each_value.length; i += 1) {
 					var each_context = assign(assign({}, ctx), {
 						each_value: each_value,