Rename js snippets

snippets/js/s/transform-object.md

@@ -0,0 +1,29 @@
+---
+title: Transform object
+type: snippet
+language: javascript
+tags: [object]
+cover: green-plant
+dateModified: 2020-10-22T20:24:44+03:00
+---
+
+Applies a function against an accumulator and each key in the object (from left to right).
+
+- Use `Object.keys()` to iterate over each key in the object.
+- Use `Array.prototype.reduce()` to apply the specified function against the given accumulator.
+
+```js
+const transform = (obj, fn, acc) =>
+  Object.keys(obj).reduce((a, k) => fn(a, obj[k], k, obj), acc);
+```
+
+```js
+transform(
+  { a: 1, b: 2, c: 1 },
+  (r, v, k) => {
+    (r[v] || (r[v] = [])).push(k);
+    return r;
+  },
+  {}
+); // { '1': ['a', 'c'], '2': ['b'] }
+```