Rename js snippets

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

@@ -0,0 +1,23 @@
+---
+title: Max array value based on function
+type: snippet
+language: javascript
+tags: [math,array]
+cover: digital-nomad-4
+dateModified: 2020-10-21T21:54:53+03:00
+---
+
+Returns the maximum value of an array, after mapping each element to a value using the provided function.
+
+- Use `Array.prototype.map()` to map each element to the value returned by `fn`.
+- Use `Math.max()` to get the maximum value.
+
+```js
+const maxBy = (arr, fn) =>
+  Math.max(...arr.map(typeof fn === 'function' ? fn : val => val[fn]));
+```
+
+```js
+maxBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], x => x.n); // 8
+maxBy([{ n: 4 }, { n: 2 }, { n: 8 }, { n: 6 }], 'n'); // 8
+```