From 22c17f9b7a062102c1dcd173416f2d3eea40c385 Mon Sep 17 00:00:00 2001
From: Scotty Simpson <portrayme@mac.com>
Date: Thu, 9 May 2019 06:26:33 -0700
Subject: [PATCH] document DOM binding undefined warning

A child's DOM node bound from a parent's empty prop throws a warning. This explains it and shows how to suppress.
---
 site/content/docs/02-template-syntax.md | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/site/content/docs/02-template-syntax.md b/site/content/docs/02-template-syntax.md
index 917673a7b0..9e509aa735 100644
--- a/site/content/docs/02-template-syntax.md
+++ b/site/content/docs/02-template-syntax.md
@@ -553,6 +553,27 @@ To get a reference to a DOM node, use `bind:this`.
 <canvas bind:this={canvasElement}></canvas>
 ```
 
+Note that binding a property of a parent component to a child component's DOM node will throw a warning unless the property is assigned a default value:
+
+```html
+<!-- Child.svelte -->
+<script>
+  export let inputElement
+</script>
+
+<input bind:this={inputElement} />
+
+...
+
+<!-- Parent.svelte -->
+<script>
+  let inputElement
+</script>
+
+<Child bind:inputElement>
+```
+
+Assign a non-`undefined` value in either component to suppress the warning.
 
 ### Component bindings