From c58488d1e71a279360d79c700e05ffbc0e8a31e4 Mon Sep 17 00:00:00 2001
From: atomiks <cc.glows@gmail.com>
Date: Tue, 2 Jan 2018 09:40:46 +1100
Subject: [PATCH 1/3] Add once snippet

---
 snippets/once.md | 27 +++++++++++++++++++++++++++
 tag_database     |  1 +
 2 files changed, 28 insertions(+)
 create mode 100644 snippets/once.md

diff --git a/snippets/once.md b/snippets/once.md
new file mode 100644
index 000000000..a3b3e6adb
--- /dev/null
+++ b/snippets/once.md
@@ -0,0 +1,27 @@
+### once
+
+Ensures a function is called only once.
+
+Utilizing a closure, use a variable flag and set it to true once the function is called
+for the first time, preventing it from being called again. Allow the function to be supplied
+with an arbitrary number of arguments using the spread/rest (`...`) operator.
+
+```js
+const once = fn => {
+  let called = false;
+  return (...args) => {
+    if (!called) {
+      fn(...args);
+      called = true;
+    }
+  };
+};
+```
+
+```js
+const startApp = event => {
+  // initializes the app
+  console.log(event); // access to any arguments supplied
+};
+document.addEventListener('click', once(startApp)); // only runs `startApp` once upon click
+```
diff --git a/tag_database b/tag_database
index 708f71b32..19bf1cbab 100644
--- a/tag_database
+++ b/tag_database
@@ -95,6 +95,7 @@ negate:logic
 nthElement:array
 objectFromPairs:object
 objectToPairs:object
+once:function
 onUserInputChange:browser
 orderBy:object
 palindrome:string

From 96b88893e39aa3e299e28800049c8a48eb7c9854 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Tue, 2 Jan 2018 10:44:42 +0200
Subject: [PATCH 2/3] Update once.md

---
 snippets/once.md | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/snippets/once.md b/snippets/once.md
index a3b3e6adb..01d6216d1 100644
--- a/snippets/once.md
+++ b/snippets/once.md
@@ -2,9 +2,8 @@
 
 Ensures a function is called only once.
 
-Utilizing a closure, use a variable flag and set it to true once the function is called
-for the first time, preventing it from being called again. Allow the function to be supplied
-with an arbitrary number of arguments using the spread/rest (`...`) operator.
+Utilizing a closure, use a flag, `called`, and set it to `true` once the function is called for the first time, preventing it from being called again. 
+Allow the function to be supplied with an arbitrary number of arguments using the spread (`...`) operator.
 
 ```js
 const once = fn => {

From 5011497935a84cc0d9556e510d87d573a55a07f1 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Tue, 2 Jan 2018 10:48:08 +0200
Subject: [PATCH 3/3] Updated to use @skatcat31's suggestion

---
 snippets/once.md | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/snippets/once.md b/snippets/once.md
index 01d6216d1..18e5fc886 100644
--- a/snippets/once.md
+++ b/snippets/once.md
@@ -6,15 +6,7 @@ Utilizing a closure, use a flag, `called`, and set it to `true` once the functio
 Allow the function to be supplied with an arbitrary number of arguments using the spread (`...`) operator.
 
 ```js
-const once = fn => {
-  let called = false;
-  return (...args) => {
-    if (!called) {
-      fn(...args);
-      called = true;
-    }
-  };
-};
+const once = fn => (called => (...args) => !called ? (called = true, fn(...args)) : undefined)()
 ```
 
 ```js