From 92cb04434ff7ec57b7e43bc46b4d6300c9dccb30 Mon Sep 17 00:00:00 2001
From: Tansica Sun <42325298+tjs13@users.noreply.github.com>
Date: Tue, 13 Nov 2018 20:13:34 -0800
Subject: [PATCH] Clarified + in addition and concatenation (#21433)

Distinguished `+` function (arithmetic versus concatenation) when dealing with different data types (number versus string).
---
 .../english/javascript/arithmetic-operation/index.md | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/guide/english/javascript/arithmetic-operation/index.md b/guide/english/javascript/arithmetic-operation/index.md
index 0e8f22b134..5ed60719fe 100644
--- a/guide/english/javascript/arithmetic-operation/index.md
+++ b/guide/english/javascript/arithmetic-operation/index.md
@@ -9,9 +9,21 @@ JavaScript provides five arithmetic operators: `+`, `-`, `*`, `/` and `%`. The o
 
 `a + b`
 
+**Caution**
+<br>
+The `+` serves as an arithmetic operator and for concatenating strings. Take extra caution when dealing with numbers versus string data types.
+
+If `a` and `b` data types are both numbers, their value will add.
+<br>
+If `a` is a number and `"b"` is a string, their value will concatenate into a string.
+<br>
+If `"a"` and `"b"` are both strings, their value will concatenate into a string.
+
 **Usage**
 
     2 + 3          // returns 5
+    5 + "3"        // returns "53"
+    "10" + "40"    // returns "1040"
     true + 2       // interprets true as 1 and returns 3
     false + 5      // interprets false as 0 and returns 5
     true + "bar"   // concatenates the boolean value and returns "truebar"