Rename js snippets

snippets/js/s/array-head.md

@@ -0,0 +1,24 @@
+---
+title: Head of array
+type: snippet
+language: javascript
+tags: [array]
+cover: clay-pot-horizon
+dateModified: 2020-10-19T22:49:51+03:00
+---
+
+Returns the head of an array.
+
+- Check if `arr` is truthy and has a `length` property.
+- Use `arr[0]` if possible to return the first element, otherwise return `undefined`.
+
+```js
+const head = arr => (arr && arr.length ? arr[0] : undefined);
+```
+
+```js
+head([1, 2, 3]); // 1
+head([]); // undefined
+head(null); // undefined
+head(undefined); // undefined
+```