From c7cca9bad25240a1c55a81cd2d16321ca9101402 Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Tue, 2 Jan 2018 13:05:39 +1100
Subject: [PATCH 1/4] Update memoize to use a map and allow access to it

---
 snippets/memoize.md | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/snippets/memoize.md b/snippets/memoize.md
index c1b6b1343..174812f26 100644
--- a/snippets/memoize.md
+++ b/snippets/memoize.md
@@ -2,13 +2,16 @@
 
 Returns the memoized (cached) function.
 
-Use `Object.create(null)` to create an empty object without `Object.prototype` (so that those properties are not resolved if the input value is something like `'hasOwnProperty'`).
+Create an empty cache using by instantiating a new `Map` object.
 Return a function which takes a single argument to be supplied to the memoized function by first checking if the function's output for that specific input value is already cached, or store and return it if not.
+Allow access to the `cache` by setting it as a property on the returned function.
 
 ```js
 const memoize = fn => {
-  const cache = Object.create(null);
-  return value => cache[value] || (cache[value] = fn(value));
+  const cache = new Map();
+  const cached = val => cache.get(val) || (cache.set(val, fn(val))) && cache.get(val);
+  cached.cache = cache;
+  return cached;
 };
 ```
 
@@ -17,4 +20,5 @@ const memoize = fn => {
 const anagramsCached = memoize(anagrams);
 anagramsCached('javascript'); // takes a long time
 anagramsCached('javascript'); // returns virtually instantly since it's now cached
+console.log(anagramsCached.cache); // Map
 ```

From 116f68d89db3c0779bf0a66de95f3d8851e97851 Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Tue, 2 Jan 2018 14:29:08 +1100
Subject: [PATCH 2/4] Update memoize.md

---
 snippets/memoize.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/memoize.md b/snippets/memoize.md
index 174812f26..f945b645d 100644
--- a/snippets/memoize.md
+++ b/snippets/memoize.md
@@ -2,7 +2,7 @@
 
 Returns the memoized (cached) function.
 
-Create an empty cache using by instantiating a new `Map` object.
+Create an empty cache by instantiating a new `Map` object.
 Return a function which takes a single argument to be supplied to the memoized function by first checking if the function's output for that specific input value is already cached, or store and return it if not.
 Allow access to the `cache` by setting it as a property on the returned function.
 

From 77d89d949c9c5cb5c09512fdb34dc1faca5b981f Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Tue, 2 Jan 2018 15:06:52 +1100
Subject: [PATCH 3/4] Update memoize.md

---
 snippets/memoize.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/snippets/memoize.md b/snippets/memoize.md
index f945b645d..7df16e542 100644
--- a/snippets/memoize.md
+++ b/snippets/memoize.md
@@ -9,7 +9,7 @@ Allow access to the `cache` by setting it as a property on the returned function
 ```js
 const memoize = fn => {
   const cache = new Map();
-  const cached = val => cache.get(val) || (cache.set(val, fn(val))) && cache.get(val);
+  const cached = val => cache.has(val) ? cache.get(val) : (cache.set(val, fn(val)) && cache.get(val));
   cached.cache = cache;
   return cached;
 };

From f70595f36cbc62ce4fe6b7fe4975b9169dbf5070 Mon Sep 17 00:00:00 2001
From: atomiks <sprytex@gmail.com>
Date: Wed, 3 Jan 2018 05:10:16 +1100
Subject: [PATCH 4/4] Update memoize.md

---
 snippets/memoize.md | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/snippets/memoize.md b/snippets/memoize.md
index 7df16e542..856375a69 100644
--- a/snippets/memoize.md
+++ b/snippets/memoize.md
@@ -3,13 +3,17 @@
 Returns the memoized (cached) function.
 
 Create an empty cache by instantiating a new `Map` object.
-Return a function which takes a single argument to be supplied to the memoized function by first checking if the function's output for that specific input value is already cached, or store and return it if not.
+Return a function which takes a single argument to be supplied to the memoized function by first checking if the function's output for that specific input value is already cached, or store and return it if not. The `function` keyword must be used in order to allow the memoized function to have its `this` context changed if necessary.
 Allow access to the `cache` by setting it as a property on the returned function.
 
 ```js
 const memoize = fn => {
   const cache = new Map();
-  const cached = val => cache.has(val) ? cache.get(val) : (cache.set(val, fn(val)) && cache.get(val));
+  const cached = function(val) {
+    return cache.has(val)
+      ? cache.get(val)
+      : cache.set(val, fn.call(this, val)) && cache.get(val);
+  };
   cached.cache = cache;
   return cached;
 };