Check for Palindromes- I dunno whats wrong with my code

Check for Palindromes- I dunno whats wrong with my code

Tell us what’s happening:

Your code so far

function palindrome(str) {
  // Good luck!
 str = str.replace(/[&\/\\#,+()$~%.'":*?<>{} ]/g,'');
 str = str.toLowerCase;
  var i;
  var newStr = "";
    for(i = str.length-1; i >= 0; i--) {
        newStr = newStr + x[i];
  if(newStr == str)
        return true;
    return false;


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Link to the challenge:



3 steps

first is str.replace, the chosen characters dont pass all the tests

str = str.replace(/[&\/\\#,+()$~%.'":*?<>{} ]/g,'');

lets make it

str = str.replace(/[^A-Za-z0-9]/g,'');

it’s now replacing all non alphanumeric characters, notice the ^ symbol, which basically reverses the regular expression to find anything that isnt within A-Z a-z or 0-9

you left off the parenthesis at the end of

str = str.toLowerCase;  // should be str=str.toLowerCase();


for(i = str.length-1; i >= 0; i--) {
        newStr = newStr + x[i]; // should be str[i]

in your for loop you reference x[i]; but you never declared a variable x.
you need it to be str[i]

Good luck!



Thanks I made all the changes and it worked like a charm. So, silly of me for not declaring x.
Thanks for your help :slight_smile:

1 Like


Also way using a regular expression to replace all non-alphanumeric characters is:

str = str.replace(/\W|_/g,'');

The \W metacharacter is used to find a non-word character. A word character is a character from a-z, A-Z, 0-9, including the _ (underscore) character.

The | stands for OR.

The _ is to find underscore characters. This has to be in here, because the \W does not consider the underscore to be a non-word character.

Putting it all together the regular expression replaces all non-word characters and underscores with a blank string.



Thanks for your explanation :slight_smile: I will come up with more query :smiley: