JavaScript: Alphanumeric characters that are palindromes

Last update on November 01 2022 16:10:33 (UTC/GMT +8 hours)

JavaScript String: Exercise-50 with Solution

A palindrome is a word, number, phrase, or other sequence of symbols that reads the same backwards as forwards, such as the words madam or racecar, the date/time stamps 11/11/11 11:11 and 02/02/2020, and the sentence: "A man, a plan, a canal – Panama". The 19-letter Finnish word saippuakivikauppias (a soapstone vendor), is the longest single-word palindrome in everyday use, while the 12-letter term tattarrattat (from James Joyce in Ulysses) is the longest in English.
Write a JavaScript program to check if a given string contains alphanumeric characters that are palindromes regardless of special characters and letter case.
Test Data:
('$22_|1372^2731|_22') -> true
('12%^&2') -> false
('234%$$%432') -> true
(1234) -> "It must be string"
('aba%$aba') -> true
('Aba%$aba') -> true

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript function to check Alphanumeric characters that are palindromes</title>
</head>
<body>

</body>
</html>

JavaScript Code:

const test = (alpha_text) => {
  if (typeof alpha_text !== 'string') {
    return 'It must be string'
  }

  const new_text = alpha_text.replace(/[^a-z0-9]+/ig, '').toLowerCase()
  const mid_index = new_text.length >> 1  

  for (let i = 0; i < mid_index; i++) {
    if (new_text.at(i) !== new_text.at(~i))
    {  
      return false
    }
  }

  return true
}
console.log(test('$22_|1372^2731|_22'))
console.log(test('12%^&2'))
console.log(test('234%$$%432'))
console.log(test(1234))
console.log(test('aba%$aba'))
console.log(test('Aba%$aba'))

Sample Output:

true
false
true
It must be string
true
true

Flowchart:

Live Demo:

See the Pen javascript-string-exercise-50 by w3resource (@w3resource) on CodePen.

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