From 5d34f752b838c72ea69d6138ad2bf1a5c8376f21 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Thu, 15 Nov 2018 22:04:19 -0500
Subject: [PATCH] only apply reactivity to assignments to top-level variables

---
 src/compile/Component.ts | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/compile/Component.ts b/src/compile/Component.ts
index 258ecade2d..03f3196fd8 100644
--- a/src/compile/Component.ts
+++ b/src/compile/Component.ts
@@ -543,6 +543,8 @@ export default class Component {
 			}
 		});
 
+		const top_scope = scope;
+
 		walk(js.content, {
 			enter(node) {
 				if (map.has(node)) {
@@ -551,7 +553,15 @@ export default class Component {
 
 				if (node.type === 'AssignmentExpression') {
 					const { name } = flattenReference(node.left);
-					code.appendLeft(node.end, `; $$make_dirty('${name}')`);
+
+					if (scope.findOwner(name) === top_scope) {
+						// TODO verify that it needs to be reactive, i.e. is
+						// used in the template (and not just in an event
+						// handler or transition etc)
+
+						// TODO handle arrow function expressions etc
+						code.appendLeft(node.end, `; $$make_dirty('${name}')`);
+					}
 				}
 
 			},