The palindrome checking function is malfunctioning and needs to be fixed

Question

The palindrome checking function is malfunctioning and needs to be fixed

I have attempted to create a function to determine if a number is a palindrome, but it seems to be malfunctioning. The concept is simple - splitting the number into two halves, comparing them, and reversing one half to check for symmetry.

function palindromeChecker(number) {
  let numArray  = String(number).split('');
  let firstHalf = numArray.slice(0, numArray.length / 2);
  let secondHalf = numArray.slice(numArray.length / 2, numArray.length);
  if (secondHalf.length > firstHalf.length) {
    secondHalf.shift();
  }
  console.log(firstHalf)
  console.log(secondHalf.reverse())
  return firstHalf == secondHalf.reverse();
}

console.log(palindromeChecker(1234321));

Although I was optimistic about the outcome, viewing both arrays and the final boolean result displayed:

[ '1', '2', '3' ]
[ '1', '2', '3' ]
false

If anyone can shed light on this issue, I would greatly appreciate it. Thank you!

javascript arrays function

Answer 1

Answer №1

According to the JavaScript documentation, the .reverse() method reverses the array in-place.

For example, when you use array2.reverse(), you are essentially reversing the actual second half of the array as well (resulting in [1,2,3]).

Subsequently, when you compare the two halves with the statement:

array1 == array2.reverse();

You are actually comparing [1,2,3] with [3,2,1]. Therefore, only reverse it once to prevent this discrepancy.

Additionally

Understanding array equality in JavaScript can be tricky, as shown in this Stack Overflow thread.

[1,2,3]==[1,2,3] // false

You may consider using:

JSON.stringify(arr1) === JSON.stringify(arr2);

or

const isEqual = arr1.length === arr2.length && arr1.every((value, index) => value === arr2[index]);

Answer 2

According to the JavaScript documentation, the .reverse() method reverses the array in-place.

For example, when you use array2.reverse(), you are essentially reversing the actual second half of the array as well (resulting in [1,2,3]).

Subsequently, when you compare the two halves with the statement:

array1 == array2.reverse();

You are actually comparing [1,2,3] with [3,2,1]. Therefore, only reverse it once to prevent this discrepancy.

Additionally

Understanding array equality in JavaScript can be tricky, as shown in this Stack Overflow thread.

[1,2,3]==[1,2,3] // false

You may consider using:

JSON.stringify(arr1) === JSON.stringify(arr2);

or

const isEqual = arr1.length === arr2.length && arr1.every((value, index) => value === arr2[index]);

Answer 3

Answer №2

array1 and array2.reverse() have values that are not based on their content, but rather on their system address.

To transform your array into a string:

function luckyNumber(value)
  {
  let 
    arr  = [...value.toString(10)]
  , str1 = arr.slice(0, arr.length / 2).join('')
  , str2 = arr.slice(arr.length / 2, arr.length).reverse().join('')
    ;
  if (str2.length > str1.length) 
    str2 = str2.slice(0,-1); 

  console.log( str1 , str2 )

  return str1 === str2;
  }

  console.log(luckyNumber(1234321));

Answer 4

array1 and array2.reverse() have values that are not based on their content, but rather on their system address.

To transform your array into a string:

function luckyNumber(value)
  {
  let 
    arr  = [...value.toString(10)]
  , str1 = arr.slice(0, arr.length / 2).join('')
  , str2 = arr.slice(arr.length / 2, arr.length).reverse().join('')
    ;
  if (str2.length > str1.length) 
    str2 = str2.slice(0,-1); 

  console.log( str1 , str2 )

  return str1 === str2;
  }

  console.log(luckyNumber(1234321));

Answer 5

Answer №3

Comparing arrays requires a specific approach, try this method instead:

return JSON.stringify(array1) === JSON.stringify(array2);

I once encountered a similar situation and adapted the solution to fit your requirements:

function checkPalindrome(value) {
let stringValue = String(value);

  let sizeOfString = stringValue.length;
  
  for(let i = 0; i < sizeOfString / 2; i++){
      if(stringValue[i] !== stringValue[sizeOfString - 1 - i]){
          return false;
      }
  }
  return true;
}

console.log(checkPalindrome(1234321));
console.log(checkPalindrome(1234320));
console.log(checkPalindrome(1234311));
console.log(checkPalindrome(12344321));

Answer 6

Comparing arrays requires a specific approach, try this method instead:

return JSON.stringify(array1) === JSON.stringify(array2);

I once encountered a similar situation and adapted the solution to fit your requirements:

function checkPalindrome(value) {
let stringValue = String(value);

  let sizeOfString = stringValue.length;
  
  for(let i = 0; i < sizeOfString / 2; i++){
      if(stringValue[i] !== stringValue[sizeOfString - 1 - i]){
          return false;
      }
  }
  return true;
}

console.log(checkPalindrome(1234321));
console.log(checkPalindrome(1234320));
console.log(checkPalindrome(1234311));
console.log(checkPalindrome(12344321));

The palindrome checking function is malfunctioning and needs to be fixed

Answer №1

Answer №2

Answer №3

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