From 696f72ce2581a8becafd37089ab6f56fcc06f3f6 Mon Sep 17 00:00:00 2001
From: Eduardo San Martin Morote <posva@users.noreply.github.com>
Date: Fri, 18 Jan 2019 14:12:40 +0100
Subject: [PATCH] Add comments about $watch behavior with a function (#1946)

---
 src/v2/api/index.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/v2/api/index.md b/src/v2/api/index.md
index 1e501b13a..667a5181a 100644
--- a/src/v2/api/index.md
+++ b/src/v2/api/index.md
@@ -1488,6 +1488,9 @@ updated: 2018-12-26
   // 関数
   vm.$watch(
     function () {
+      // everytime the expression `this.a + this.b` yields a different result,
+      // the handler will be called. It's as if we were watching a computed
+      // property without defining the computed property itself
       return this.a + this.b
     },
     function (newVal, oldVal) {