add palindromes

Author: Connor Leech

udemy-interview-bootcamp-course/palindromes.js

@@ -0,0 +1,39 @@
+// --- Directions
+// Given a string, return true if the string is a palindrome
+// or false if it is not.  Palindromes are strings that
+// form the same word if it is reversed. *Do* include spaces
+// and punctuation in determining if the string is a palindrome.
+// --- Examples:
+//   palindrome("abba") === true
+//   palindrome("abcdefg") === false
+
+function palindrome(str){
+	const middle = Math.floor(str.length/2);
+
+	const firsthalf  = str.substring(0, middle);
+	const secondhalf = (str.length % 2 === 0)? str.substring(middle) : str.substring(middle + 1);
+	
+	return (firsthalf === reverse(secondhalf));
+}
+
+function reverse(str){
+	return str.split('').reduce((accum, letter)=> letter + accum, '');
+}
+
+
+// first solution. No need for splitting the terms into halves!
+function palindromeSolution1(str){
+	const reversed = str.split('').reduce((accum, letter)=> letter + accum, '');
+	return reversed === str;
+}
+
+
+// second solution: compare each letter from beginning and end of array
+function palindromeSolution2(str){
+	return str.split('').every((current, index, arr)=>{
+		return (current === arr[arr.length - index - 1]);
+	});
+}
+
+console.log(palindromeSolution2("abba"));
+console.log(palindromeSolution2("abcdefg"));