Update takeWhile snippets

Add takeUntil snippets

snippets/takeRightWhile.md

@@ -3,16 +3,22 @@ title: takeRightWhile
 tags: array,intermediate
 ---
 
-Removes elements from the end of an array until the passed function returns `true`.
+Removes elements from the end of an array until the passed function returns `false`.
 Returns the removed elements.
 
-- Loop through the array, using `Array.prototype.reduceRight()` and accumulating elements while `func` returns falsy values.
+- Create a reversed copy of the array, using the spread operator (`...`) and `Array.prototype.reverse()`.
+- Loop through the reversed copy, using a `for...of` loop over `Array.prototype.entries()` until the returned value from the function is falsy.
+- Return the removed elements, using `Array.prototype.slice()`.
+- The callback function, `fn`, accepts a single argument which is the value of the element.
 
 ```js
-const takeRightWhile = (arr, func) =>
-  arr.reduceRight((acc, el) => (func(el) ? acc : [el, ...acc]), []);
+const takeRightWhile = (arr, fn) => {
+  for (const [i, val] of [...arr].reverse().entries())
+    if (!fn(val)) return i === 0 ? [] : arr.slice(-i);
+  return arr;
+};
 ```
 
 ```js
-takeRightWhile([1, 2, 3, 4], n => n < 3); // [3, 4]
+takeRightWhile([1, 2, 3, 4], n => n >= 3); // [3, 4]
 ```