feat: add Strings section with checkPalindrome algorithm

Strings/checkPalindrome.js

@@ -0,0 +1,40 @@
+// JavaScript implementation of palindrome check
+// More details: https://medium.freecodecamp.org/two-ways-to-check-for-palindromes-in-javascript-64fea8191fd7
+/**
+ * @description Check if the input is a palindrome
+ * 
+ * @param {string|number} input
+ * @returns {boolean} is input a palindrome?
+ */
+function checkPalindrome(input) {
+    // Only strings and numbers can be palindrome
+    if (typeof input !== 'string' && typeof input !== 'number') {
+        return null;
+    }
+
+    // Convert given number to string
+    if (typeof input === 'number') {
+        input = String(input);
+    }
+
+    return input === input.split('').reverse().join('');
+}
+
+// Test
+let input = 'ABCDCBA';
+console.log(checkPalindrome(input)); // true
+
+input = 12321;
+console.log(checkPalindrome(input)); // true
+
+input = 123.321;
+console.log(checkPalindrome(input)); // true
+
+input = 'ABCD';
+console.log(checkPalindrome(input)); // false
+
+input = 123.4;
+console.log(checkPalindrome(input)); // false
+
+input = {};
+console.log(checkPalindrome(input)) // null