Rename js snippets

snippets/js/s/pick-matching-object-keys.md

@@ -0,0 +1,26 @@
+---
+title: Pick matching object keys
+type: snippet
+language: javascript
+tags: [object]
+cover: lake-bench
+dateModified: 2020-10-22T20:24:04+03:00
+---
+
+Creates an object composed of the properties the given function returns truthy for.
+
+- Use `Object.keys()` and `Array.prototype.filter()`to remove the keys for which `fn` returns a falsy value.
+- Use `Array.prototype.reduce()` to convert the filtered keys back to an object with the corresponding key-value pairs.
+- The callback function is invoked with two arguments: (value, key).
+
+```js
+const pickBy = (obj, fn) =>
+  Object.keys(obj)
+    .filter(k => fn(obj[k], k))
+    .reduce((acc, key) => ((acc[key] = obj[key]), acc), {});
+```
+
+```js
+pickBy({ a: 1, b: '2', c: 3 }, x => typeof x === 'number');
+// { 'a': 1, 'c': 3 }
+```