compare two strings

**xravensxdreamx** · 03-10-2010, 09:33 PM

How do I take two strings and compare them? My last attempt was to put them into arrays but that causes an error. I am stuck.

<script type="text/javascript">
/* <![CDATA[ */
//declare s1 as a variable and prompt user for a word
var s1 = prompt("enter a word");
s1 = s1.toUpperCase() // make word upper case
var j;
// reverses the word entered by the user
for (var i = s1.length - 1; i>=0; i--, j++)
{
var s2 = s1; // take word that was reversed and put it in s2
}
// turn them into an array
var arrays = new array();
var array1[] = s1;
var array2[] = s2;

// compare the arrays and display message
for( var j=0;j<array1.length;j++)
{
if(array1[j] == array2[j])
{
alert( s1 + " is a palindrome");
else
alert( s1 + " is not a palindrome");
}
}
// compare the words and display a message
//if (s1 == s2)
//alert( s1 + " is a palindrome");
//else
// alert( s1 + " is not a palindrome");
/* ]]> */
</script>

**JMRKER** · 03-10-2010, 09:55 PM

No need to use arrays. Not the best way to do this, but for simple words it will work.

Note: No checks for punctuation or spaces if used to check for palindrome phrases.

Code:

<html>
<head>
<title>Palindrome Check</title>
</head>
<body>
<script type="text/javascript">
// From: http://www.webdeveloper.com/forum/showthread.php?t=226128

//declare s1 as a variable and prompt user for a word
var s1 = prompt("enter a word");

// reverses the word entered by the user
function reverseWord(s1) {
  s1 = s1.toUpperCase() // make word upper case
  var s2 = '';
  for (var i = s1.length - 1; i>=0; i--) {
    s2 += s1[i]; // take word that was reversed and put it in s2
  }
  return s2;
}

/* INVALID ARRAY ASSIGNMENT
// turn them into an array
var arrays = new array();
var array1[] = s1;
var array2[] = s2;
*/

// compare the words and display message
  if(s1.toUpperCase() == reverseWord(s1)) {
    alert( s1 + " is a palindrome");
  } else {
    alert( s1 + " is not a palindrome");
  }

// compare the words and display a message
//if (s1 == s2)
//alert( s1 + " is a palindrome");
//else
// alert( s1 + " is not a palindrome");

</script> 
</body>
</html>

Note: remove extra comments from original post after you see why it was not needed.

BTW: Please use [ code] and [ /code] tags (without the spaces)
to make it easier to read you code in the forum.

**Gozzy82** · 03-11-2010, 08:16 AM

you can shorten this up a bit

function isAPalinDrom(txt){
txt = txt.toUpperCase(); // make uppercase like above function
return txt.split('').reverse().join('') === txt;
}

edit
extending the string object is a better solution:

http://www.webdeveloper.com/forum/sh...d.php?t=226121
/edit

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