Add logical complement

snippets/complement.md

@@ -0,0 +1,19 @@
+---
+title: complement
+tags: function,logic,beginner
+---
+
+Returns a function that is the logical complement of the given function, `fn`.
+
+Use the logical not (`!`) operator on the result of calling `fn` with any supplied `args`.
+
+```js
+const complement = fn => (...args) => !fn(...args);
+```
+
+```js
+const isEven = num => num % 2 === 0;
+const isOdd = complement(isEven);
+isOdd(2); // false
+isOdd(3); // true
+```