From f7d5892fa071425bd6cfb9f6501a3c7e5d2c82be Mon Sep 17 00:00:00 2001
From: Steven Huang <stevenhuang1995@gmail.com>
Date: Wed, 20 Nov 2019 05:31:02 -0500
Subject: [PATCH] site: reactive statements, avoid infinite loops

Add a blurb to describe how reactive statements can be configured to run only when certain values have changed.
---
 site/content/docs/01-component-format.md | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/site/content/docs/01-component-format.md b/site/content/docs/01-component-format.md
index 3d349af51d..a464065eb3 100644
--- a/site/content/docs/01-component-format.md
+++ b/site/content/docs/01-component-format.md
@@ -130,6 +130,23 @@ Any top-level statement (i.e. not inside a block or a function) can be made reac
 
 ---
 
+To avoid infinite loops, reactive statements can be configured to run only when certain values have changed.
+
+```html
+<script>
+	export let x, y, z;
+	
+	function dosomething() {
+	    z = x + y;
+	}
+	// this will execute `dosomething()` whenever
+	// `x` or `y` prop changes, but not `z`
+	$: x, y, dosomething();
+</script>
+```
+
+---
+
 If a statement consists entirely of an assignment to an undeclared variable, Svelte will inject a `let` declaration on your behalf.
 
 ```html