adding AlphaNumericPalindrome.js, an algorithm question from freecode

Author: Syed Fasiuddin

String/AlphaNumericPalindrome.js

@@ -0,0 +1,64 @@
+/**
+ * alphaNumericPlaindrome should return true if the string has alphanumeric characters that are palindrome irrespective of special characters and the letter case
+ * @param {string} str the string to check
+ * @returns `Boolean`
+ */
+
+/*****************************************************************************
+ * What is a palindrome? https://en.wikipedia.org/wiki/Palindrome
+ * 
+ * The function alphaNumericPlaindrome() recieves a sting with varying formats
+ * like "racecar", "RaceCar", and "race CAR"
+ * The string can also have special characters 
+ * like "2A3*3a2", "2A3 3a2", and "2_A3*3#A2"
+ * 
+ * But the catch is, we have to check only if the alphanumeric characters 
+ * are palindrome i.e remove spaces, symbols, punctuations etc 
+ * and the case of the characters doesn't matter
+ * 
+ * This is one of the questions/projects that we have to solve for the 
+ * JavaScript Algorithms and Data Structures course on https://www.freecodecamp.org
+ * 
+ * Author -- Syed Fasiuddin 
+ * https://github.com/SyedFasiuddin
+ * 
+ ****************************************************************************/
+
+const alphaNumericPlaindrome = (str) => {
+    // removing all the special characters and turning everything to lowercase
+    let newStr = str.replace(/[^a-zA-Z0-9]*/g, "").toLowerCase();
+    // the newStr variable is a string and only has alphanumeric characters all in lowercase
+
+    // making an array of individual characters as it's elements
+    let arr = newStr.split("")
+
+    // setting a variable to see if change occurs to it 
+    let palin = 0;
+
+    // making a copy of arr with spread operator
+    let arrRev = [...arr];
+    // you can use arrRev.reverse() to reverse the array
+    // or else you can use the below method 
+
+    // iterate through the arr and check the condition of palindrome
+    for (let i = 0; i < arr.length; i++) {
+        if (arr[i] !== arrRev[arr.length - 1 - i]) {
+            // if the string is not palindrome then we change palin varaible to 1
+            palin = 1
+        }
+    }
+
+    // if the string is palindrome then palin variable is never changed
+    if (palin == 0) return true;
+    else return false;
+}
+
+
+// test cases
+// alphaNumericPlaindrome("eye");
+// alphaNumericPlaindrome("0_0 (: /-\ :) 0-0")
+// alphaNumericPlaindrome("five|\_/|four")
+// alphaNumericPlaindrome("A man, a plan, a canal. Panama")
+
+
+export { alphaNumericPlaindrome }