Rename js snippets

snippets/js/s/function-based-array-min-max.md

@@ -0,0 +1,31 @@
+---
+title: Min and max of array based on provided function
+type: snippet
+language: javascript
+tags: [array]
+cover: orange-coffee
+dateModified: 2020-11-03T22:11:18+02:00
+---
+
+Returns the minimum/maximum value of an array, after applying the provided function to set the comparing rule.
+
+- Use `Array.prototype.reduce()` in combination with the `comparator` function to get the appropriate element in the array.
+- Omit the second argument, `comparator`, to use the default one that returns the minimum element in the array.
+
+```js
+const reduceWhich = (arr, comparator = (a, b) => a - b) =>
+  arr.reduce((a, b) => (comparator(a, b) >= 0 ? b : a));
+```
+
+```js
+reduceWhich([1, 3, 2]); // 1
+reduceWhich([1, 3, 2], (a, b) => b - a); // 3
+reduceWhich(
+  [
+    { name: 'Tom', age: 12 },
+    { name: 'Jack', age: 18 },
+    { name: 'Lucy', age: 9 }
+  ],
+  (a, b) => a.age - b.age
+); // {name: 'Lucy', age: 9}
+```