LC 2618. Check if Object Instance of Class (JS)

Author: raul-sauco

README.md

@@ -509,6 +509,7 @@ Solutions to LeetCode problems. The first column links to the problem in LeetCod
 | [2542. Maximum Subsequence Score][lc2542]                                                     | 🟠 Medium  | [![rust](res/rs.png)][lc2542rs]                                                                       |
 | [2543. Check if Point Is Reachable][lc2543]                                                   | 🔴 Hard    | [![python](res/py.png)][lc2543py] [![rust](res/rs.png)][lc2543rs]                                     |
 | [2585. Number of Ways to Earn Points][lc2585]                                                 | 🔴 Hard    | [![python](res/py.png)][lc2585py] [![rust](res/rs.png)][lc2585rs]                                     |
+| [2618. Check if Object Instance of Class][lc2618]                                             | 🟠 Medium  | [![js](res/js.png)][lc2618js]                                                                         |
 | [2619. Array Prototype Last][lc2619]                                                          | 🟢 Easy    | [![js](res/js.png)][lc2619js]                                                                         |
 | [2620. Counter][lc2620]                                                                       | 🟢 Easy    | [![js](res/js.png)][lc2620js]                                                                         |
 | [2621. Sleep][lc2621]                                                                         | 🟢 Easy    | [![js](res/js.png)][lc2621js]                                                                         |
@@ -1638,6 +1639,8 @@ Solutions to LeetCode problems. The first column links to the problem in LeetCod
 [lc2585]: https://leetcode.com/problems/number-of-ways-to-earn-points/
 [lc2585py]: leetcode/number-of-ways-to-earn-points.py
 [lc2585rs]: leetcode/number-of-ways-to-earn-points.rs
+[lc2618]: https://leetcode.com/problems/check-if-object-instance-of-class/
+[lc2618js]: leetcode/check-if-object-instance-of-class.js
 [lc2619]: https://leetcode.com/problems/array-prototype-last/
 [lc2619js]: leetcode/array-prototype-last.js
 [lc2620]: https://leetcode.com/problems/counter/

leetcode/check-if-object-instance-of-class.js

@@ -0,0 +1,45 @@
+// 2618. Check if Object Instance of Class
+// 🟠 Medium
+//
+// https://leetcode.com/problems/check-if-object-instance-of-class/
+//
+// Tags: Javascript
+
+// Get the provided object prototype and check if that matches the given class,
+// keep going up the prototype chain until we find one that it matches or
+// the chain ends.
+//
+// Time complexity: O(n) - It can go up the entire prototype chain or until it
+// finds a class that matches.
+// Space complexity: O(1) - The iterative version uses constant extra memory,
+// we could use a recursive version with similar logic, but it would require
+// extra memory.
+//
+// Runtime 115 ms Beats 27.90%
+// Memory 51.1 MB Beats 95.40%
+/**
+ * @param {any} obj
+ * @param {any} classFunction
+ * @return {boolean}
+ */
+var checkIfInstanceOf = function (obj, classFunction) {
+  if (
+    obj === null ||
+    obj === undefined ||
+    typeof classFunction !== "function"
+  ) {
+    return false;
+  }
+  let prot = Object.getPrototypeOf(obj);
+  while (prot !== null) {
+    if (prot === classFunction.prototype) {
+      return true;
+    }
+    prot = Object.getPrototypeOf(prot);
+  }
+  return false;
+};
+
+/**
+ * checkIfInstanceOf(new Date(), Date); // true
+ */