From fe646c25c9b564891f2035f6028b292f1835da79 Mon Sep 17 00:00:00 2001
From: Tan Li Hau <lhtan93@gmail.com>
Date: Sun, 13 Sep 2020 22:37:55 +0800
Subject: [PATCH] maintain context for transition

---
 src/compiler/compile/nodes/Transition.ts        |  2 +-
 .../render_dom/wrappers/Element/index.ts        |  4 ++++
 .../transition-js-args-dynamic/_config.js       | 15 +++++++++++++++
 .../transition-js-args-dynamic/main.svelte      | 17 +++++++++++++++++
 4 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 test/runtime/samples/transition-js-args-dynamic/_config.js
 create mode 100644 test/runtime/samples/transition-js-args-dynamic/main.svelte

diff --git a/src/compiler/compile/nodes/Transition.ts b/src/compiler/compile/nodes/Transition.ts
index a680fde46e..983a6ee6c7 100644
--- a/src/compiler/compile/nodes/Transition.ts
+++ b/src/compiler/compile/nodes/Transition.ts
@@ -34,7 +34,7 @@ export default class Transition extends Node {
 		}
 
 		this.expression = info.expression
-			? new Expression(component, this, scope, info.expression, true)
+			? new Expression(component, this, scope, info.expression)
 			: null;
 	}
 }
diff --git a/src/compiler/compile/render_dom/wrappers/Element/index.ts b/src/compiler/compile/render_dom/wrappers/Element/index.ts
index 2e35f0271f..f740560bcd 100644
--- a/src/compiler/compile/render_dom/wrappers/Element/index.ts
+++ b/src/compiler/compile/render_dom/wrappers/Element/index.ts
@@ -868,6 +868,10 @@ export default class ElementWrapper extends Wrapper {
 				block.chunks.destroy.push(b`if (detaching && ${outro_name}) ${outro_name}.end();`);
 			}
 		}
+
+		if ((intro && intro.expression && intro.expression.dependencies.size) || (outro && outro.expression && outro.expression.dependencies.size)) {
+			block.maintain_context = true;
+		}
 	}
 
 	add_animation(block: Block) {
diff --git a/test/runtime/samples/transition-js-args-dynamic/_config.js b/test/runtime/samples/transition-js-args-dynamic/_config.js
new file mode 100644
index 0000000000..513a17486a
--- /dev/null
+++ b/test/runtime/samples/transition-js-args-dynamic/_config.js
@@ -0,0 +1,15 @@
+export default {
+	test({ assert, component, target, window, raf }) {
+		component.visible = true;
+
+		const div = target.querySelector('div');
+
+		assert.equal(div.value, 0);
+
+		raf.tick(200);
+
+		div.value = 'test';
+		component.visible = false;
+		assert.equal(div.value, 'test');
+	}
+};
diff --git a/test/runtime/samples/transition-js-args-dynamic/main.svelte b/test/runtime/samples/transition-js-args-dynamic/main.svelte
new file mode 100644
index 0000000000..1bb149de32
--- /dev/null
+++ b/test/runtime/samples/transition-js-args-dynamic/main.svelte
@@ -0,0 +1,17 @@
+<script>
+	export let visible = false;
+	export let value = 0;
+
+	function foo(node, params) {
+		return {
+			duration: 100,
+			tick: () => {
+				node.value = value;
+			}
+		};
+	}
+</script>
+
+{#if visible}
+	<div transition:foo={{value}}></div>
+{/if}
\ No newline at end of file