Add flattenObject, unflattenObject

Tagged and tested. Quite complex methods btw.

snippets/unflattenObject.md

@@ -0,0 +1,32 @@
+### unflattenObject
+
+Unlatten an object with the paths for keys.
+
+Use `Object.keys(obj)` combined with `Array.reduce()` to convert flattened path node to a leaf node.
+If the value of a key contains a dot delimiter (`.`), use `Array.split('.')`, string transformations and `JSON.parse()` to create an object, then `Object.assign()` to create the leaf node.
+Otherwise, add the appropriate key-value pair to the accumulator object.
+
+```js
+const unflattenObject = obj =>
+  Object.keys(obj).reduce((acc, k) => {
+    if (k.indexOf('.') !== -1) {
+      const keys = k.split('.');
+      Object.assign(
+        acc,
+        JSON.parse(
+          '{' +
+            keys
+              .map((v, i) => (i !== keys.length - 1 ? `"${v}":{` : `"${v}":`))
+              .join('') +
+            obj[k] +
+            '}'.repeat(keys.length)
+        )
+      );
+    } else acc[k] = obj[k];
+    return acc;
+  }, {});
+```
+
+```js
+unflattenObject({ 'a.b.c': 1, d: 1 }); // { a: { b: { c: 1 } }, d: 1 }
+```