CODEWITHSUNDEEP
javascriptfunctionif-statementpalindrome
Charles Watson
Charles Watson

Reputation: 1075

Javascript: palindrome function?

I have working code for a simple word flipper:

var strFlip = function(str) {
    return str.split(" ").map(function(word) {
        return word.split("").reverse().join("");
    }).join(" ");    
};

console.log(strFlip("This is designed to swap the letter order of each word in the string"));

// "sihT si dengised ot paws eht rettel redro fo hcae drow ni eht gnirts"

I want to add an if/else to allow this code to now identify if each word in a string is a palindrome (spelled the same forward and backward ex: hannah).

So I tried continuing the .map() logic with:

var strFlip = function(str) {
  return str.split(" ").map(function(word) {
    return word.split("").reverse().join("");
      }).join(" ").toLowerCase().map(function(test) {
    if (test.split(" ") === word){
      return true;
    }else{
      return false;
    }
  }
   );
};

console.log(strFlip("Hannah loves her racecar"));

BUT.... unsurprisingly, it returns an error essentially stating that the long linked collection of functions before the if section is not itself a function:

TypeError: str.split(...).map(...).join(...).toLowerCase(...).map is not a function

I was also getting lost trying to match all of the curly braces, but I think I got them all.

So, is it possible to add the if/else within?

Upvotes: 1

Views: 662

Answers (1)

CrimsonChris
CrimsonChris

Reputation: 4651

.join(" ").toLowerCase() returns a string, not an array. The error is stating that 'some string'.map is not a function because it's undefined.

If what you want is an array that indicates whether a word at an index is a palindrome then...

var sentence = 'Eve drives a racecar',
        words = sentence.split(" ").map(function(word) {
                    var isPalindrome = word.length > 1 && (word.toLowerCase() === word.toLowerCase().split("").reverse().join(""));
                    return { text: word, isPalindrome: isPalindrome };
                });
    alert(JSON.stringify(words));

Upvotes: 2

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