From c1be98605159f99cac5e16f787cf139ab8a04e24 Mon Sep 17 00:00:00 2001
From: Angelos Chalaris <chalarangelo@gmail.com>
Date: Fri, 12 Jan 2018 14:44:20 +0200
Subject: [PATCH] Add merge

---
 snippets/merge.md | 33 +++++++++++++++++++++++++++++++++
 tag_database      |  1 +
 2 files changed, 34 insertions(+)
 create mode 100644 snippets/merge.md

diff --git a/snippets/merge.md b/snippets/merge.md
new file mode 100644
index 000000000..fbc4ec7b7
--- /dev/null
+++ b/snippets/merge.md
@@ -0,0 +1,33 @@
+### merge
+
+Creates a new object from the combination of two or more objects.
+
+Use `Array.reduce()` combined with `Object.keys(obj)` to iterate over all objects and keys.
+Use `hasOwnProperty()` and `Array.concat()` to append values for keys existing in multiple objects.
+
+```js
+const merge = (...objs) =>
+  [...objs].reduce(
+    (acc, obj) =>
+      Object.keys(obj).reduce((a, k) => {
+        acc[k] = acc.hasOwnProperty(k)
+          ? [].concat(acc[k]).concat(obj[k])
+          : obj[k];
+        return acc;
+      }, {}),
+    {}
+  );
+```
+
+```js
+const object = {
+  a: [{ x: 2 }, { y: 4 }],
+  b: 1,
+};
+const other = {
+  a: { z: 3 },
+  b: [2, 3],
+  c: 'foo',
+};
+merge(object, other); // { a: [ { x: 2 }, { y: 4 }, { z: 3 } ], b: [ 1, 2, 3 ], c: 'foo' }
+```
diff --git a/tag_database b/tag_database
index e70eef4a2..e1d4aa6aa 100644
--- a/tag_database
+++ b/tag_database
@@ -112,6 +112,7 @@ maxBy:math,array,function
 maxN:array,math
 median:math,array
 memoize:function
+merge:object,array
 minBy:math,array,function
 minN:array,amth
 negate:function