Finding palindromes and the longest word in a string

Question

I have two little projects that I've been working on.

One is to find all palindromes:

function palindrome(str) {
 var replaceStrChr = str.replace(/\W/g,'').replace(/ /g,'').replace(/_/g,'').toLowerCase();
 var arrayifyStr = replaceStrChr.split('').reverse();
 var stringifyStr = arrayifyStr.join('');
 if (replaceStrChr === stringifyStr){
 return true;
 } else {
 return false;
 }
}

And the other one is to find the longest word in a string:

function findLongestWord(str){
 var arrayify = str.split(' ');
 var longest = 0;
 for(var x = 0; x < arrayify.length; x++){
 if (arrayify[x].length > longest){
 longest = arrayify[x].length;
 }
 }
 return longest;
}

What I'm looking for is a better way to do these, shortcuts, better syntax, etc.

Answer 1

For the palindrome:

• You can probably just use one replace operation, but with a more extensive regex. My regex is rusty but something like /[\W_\s]/g could do.

• split, reverse and join could possibly be just one chain.

  var reversedString = replaceStrChr.split('').reverse().join('');
  

• Comparisons are essentially boolean values. You can simply do:

  return replaceStrChr === stringifyStr;
  

For the longest word:

• Use reduce and carry through the longest word.

  var longestWord = str.split(' ').reduce(function(prev, next){
   return next.length > prev.length ? next : prev;
  });
  

• str doesn't tell me what the string contains. Only when I saw split(' ') did I realize it was a space-separated string. Rename the variable to show its purpose.

• 13aal: length > prev.length ? next : prev; ternary?
• Joseph: @13aal Yes, that's a ternary.

Answer 2

I pretty much second everything in @Joseph the Dreamer's answer except for simplifying the palindrome.

You can simplify the regex by making it just /[\W_]/g. So, we now can get the reduced string. We do not need to check for white spaces since those are non-word characters (\W).

replaceStrChr = str.replace(/[\W_]/g, '');

Then there is no need to reverse the string then compare them. We can save time by checking it at the same time:

for(var i = 0, j = replaceStrChr.length; i < j;)
 if(replaceStrChr[i++] !== replaceStrChr[j--]) return false;
return true;

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Hope this helps!