Finding palindromes and the longest word in a string
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 &gt; 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.