Add solution #2666

Author: JoshCrozier

README.md

@@ -391,6 +391,7 @@
 2649|[Nested Array Generator](./2649-nested-array-generator.js)|Medium|
 2650|[Design Cancellable Function](./2650-design-cancellable-function.js)|Hard|
 2665|[Counter II](./2665-counter-ii.js)|Easy|
+2666|[Allow One Function Call](./2666-allow-one-function-call.js)|Easy|
 2667|[Create Hello World Function](./2667-create-hello-world-function.js)|Easy|
 2703|[Return Length of Arguments Passed](./2703-return-length-of-arguments-passed.js)|Easy|
 3110|[Score of a String](./3110-score-of-a-string.js)|Easy|

solutions/2666-allow-one-function-call.js

@@ -0,0 +1,19 @@
+/**
+ * 2666. Allow One Function Call
+ * https://leetcode.com/problems/allow-one-function-call/
+ * Difficulty: Easy
+ *
+ * Given a function fn, return a new function that is identical to the original function except
+ * that it ensures fn is called at most once.
+ *
+ * - The first time the returned function is called, it should return the same result as fn.
+ * - Every subsequent time it is called, it should return undefined.
+ */
+
+/**
+ * @param {Function} fn
+ * @return {Function}
+ */
+var once = function(fn) {
+  return (...args) => fn && [fn(...args), fn = undefined][0];
+};