Prepare repository for merge

javascript/snippets/factorial.md

@@ -0,0 +1,29 @@
+---
+title: Factorial of number
+type: snippet
+tags: [math,algorithm,recursion]
+cover: flower-vase
+dateModified: 2020-12-28T13:49:24+02:00
+---
+
+Calculates the factorial of a number.
+
+- Use recursion.
+- If `n` is less than or equal to `1`, return `1`.
+- Otherwise, return the product of `n` and the factorial of `n - 1`.
+- Throw a `TypeError` if `n` is a negative number.
+
+```js
+const factorial = n =>
+  n < 0
+    ? (() => {
+        throw new TypeError('Negative numbers are not allowed!');
+      })()
+    : n <= 1
+    ? 1
+    : n * factorial(n - 1);
+```
+
+```js
+factorial(6); // 720
+```