Member Avatar for Anthony-uk

Hi all,
today i thought id write a function to see if a string is a palindrome "a word which is spelt the same when read backwards"
and thought id post it on here, to see what other/better ways you guys had of doing it or even though i think my code works, maybe some of you see some bugs i dont know about.

anyways never posted on here before even though i have been registered for a while

<html>
	<head>
		<script type='text/javascript'>
			function handler() {
				var string = document.getElementById('string').value;
				if (true == isPalindrome(string)) {
					alert(string + ": is a palindrome");
				} else {
					alert(string + ": is not a palindrome");
				}
			}
			function isPalindrome(string) {
				if (string.length <= 1) {
					return true;
				} else if (string.charAt(0) == string.charAt(string.length-1)) {
					string = string.substring(1, string.length-1);
					return isPalindrome(string);
				} else {
					return false;
				}
			}
		</script>
	</head>
	<body>
		<button onclick='handler()'>call</button>
		<br />
		<input type='text' id='string' />
	</body>
</html>

anyways all feedback welcome

PS. i got started on this after watching a lecturer do it in python, heres the link
http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-00-introduction-to-computer-science-and-programming-fall-2008/video-lectures/lecture-4/
and jump to 42:40 on the time index

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Member Avatar for benjaminfleming 
function isPalindrome(str) {
	return (
		str.length <= 1 ||
		(str = str.toLowerCase()) ==
		str.split('').reverse().join('')
	);
}

alert(isPalindrome('RaceFastSafeCar')); // Returns true

In your method you have not set the variable to lowercase, so words that start with a capital will always return false.

Also, having a reoccurring function like that is not very efficient. It's better to make an array out of the strings characters, reverse the array, and rejoin the string.

Member Avatar for Anthony-uk

Thanks for your reply benjamin I wanted to use a recurring function "initially" to learn how they work, I like your solution to the problem, and yes capitals would come back false :)

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