09 Palindromes: Replace Regex Solution (#319)

* Replaces the original regex method, with more familiar methods
* Add descriptive comments for clarity

palindromes/palindromes.js

@@ -1,11 +1,14 @@
+// Non regex
 const palindromes = function (string) {
-  const processedString = string.toLowerCase().replace(/[^a-z]/g, "");
-  return (
-    processedString
-      .split("")
-      .reverse()
-      .join("") == processedString
-  );
+	let alphabet = 'abcdefghijklmnopqrstuvwxyz'; 				//Create a variable that holds all the letters of the alphabet
+	const cleanedString = string 						// Convert to lowercase, split, & filter only letters, rejoin as new const
+		.toLowerCase()
+		.split('')
+		.filter((letter) => alphabet.includes(letter))
+		.join('');
+	const reversedString = cleanedString.split('').reverse().join(''); 	//Create a new const that holds reversed string
+	return cleanedString === reversedString; 				//Compare cleanedString & reversedString which returns true/false
 };
 
+// Do not edit below this line
 module.exports = palindromes;