Nest all content into snippets

snippets/js/s/merge.md

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+---
+title: Merge objects
+type: snippet
+language: javascript
+tags: [object,array]
+cover: guitar-living-room
+dateModified: 2020-10-21T21:54:53+03:00
+---
+
+Creates a new object from the combination of two or more objects.
+
+- Use `Array.prototype.reduce()` combined with `Object.keys()` to iterate over all objects and keys.
+- Use `Object.prototype.hasOwnProperty()` and `Array.prototype.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' }
+```