Recursive Palindrom does not returning neither true nor false only undefined

Question

I've tried to write a recursive palindrom however, eventhough I reach at the end the true branch at the last iteration the return value is still undefined.

So if you type in the console my function with a palindrom. rekurzivSzigoruPalindrom("radar");

It will iterate through it perfectly but the return value, will be undefined. Could you please point out the error in my code below ? Thanks

function rekurzivSzigoruPalindrom(str, strLength = str.length) {
// debug eleje
console.log(strLength);
if (strLength > 1) {
console.log(str[str.length - strLength] + "  " +str[strLength-1] );
}
if(strLength == 1){
console.log(str[str.length-1]+ "   " +str[strLength-1]);
}
//debug vége
  if(typeof str == "string" || typeof str == "number"){
    if(typeof str == "number"){
       str = str.toString();
    }
  
    
    if(strLength > 1){
      if(str[str.length - strLength] == str[strLength-1]){
        //console.log(strLength);
        strLength--;
        
        rekurzivSzigoruPalindrom(str,strLength);
        }

    }
    else if(strLength == 1){
      if(str[str.length-1] == str[strLength-1]){
       console.log(strLength+"true");
        return true;
      }
      else{
        console.log(strLength+"false");
        return false;
        }    
        

      }

    }

    else {
      return false;

    }   
     
  }

Answer 1

you have to return the result of your recursive call.

function rekurzivSzigoruPalindrom(str, strLength = str.length) {
// debug eleje
console.log(strLength);
if (strLength > 1) {
console.log(str[str.length - strLength] + "  " +str[strLength-1] );
}
if(strLength == 1){
console.log(str[str.length-1]+ "   " +str[strLength-1]);
}
//debug vége
  if(typeof str == "string" || typeof str == "number"){
    if(typeof str == "number"){
       str = str.toString();
    }
  
    
    if(strLength > 1){
      if(str[str.length - strLength] == str[strLength-1]){
        //console.log(strLength);
        strLength--;
        
        return rekurzivSzigoruPalindrom(str,strLength);
        }

    }
    else if(strLength == 1){
      if(str[str.length-1] == str[strLength-1]){
       console.log(strLength+"true");
        return true;
      }
      else{
        console.log(strLength+"false");
        return false;
        }    
        

      }

    }

    else {
      return false;

    }   
     
  }