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JavaScript: Check a string for palindromes using recursion

JavaScript Function: Exercise-10 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".
Write a JavaScript program to check whether a given string is a palindrome or not using recursion.

Test Data:
("madam") -> true
("abdb") -> false
("ab") -> false
(test("a") -> true

Sample Solution:

HTML Code: 

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Check a string for palindromes using recursion</title>
</head>
<body>

</body>
</html>

JavaScript Code:

const test = (text) => {
  if (typeof text !== 'string') {
        return 'String should not be empty!'
  }

  if (text.length <= 1) {
    return true
  }

  if (text[0] !== text[text.length - 1])
  {
    return false
  } 
  else 
  {
    return test(text.slice(1, text.length - 1))
  }
}
console.log(test("madam"))
console.log(test("abdb"))
console.log(test("ab"))
console.log(test("a"))

Output:

true
false
false
true

Flowchart:

Flowchart: JavaScript recursion function- Check a string for palindromes using recursion

Live Demo:

See the Pen javascript-recursion-function-exercise-10 by w3resource (@w3resource) on CodePen.


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Next:Convert Binary to Decimal using recursion.

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JavaScript: Tips of the Day

Eequality test 

console.log(Number(2) === Number(2));
console.log(Boolean(false) === Boolean(false));
console.log(Symbol('foo') === Symbol('foo'));

Every Symbol is entirely unique. The purpose of the argument passed to the Symbol is to give the Symbol a description. The value of the Symbol is not dependent on the passed argument. As we test equality, we are creating two entirely new symbols: the first Symbol('foo'), and the second Symbol('foo'). These two values are unique and not equal to each other, Symbol('foo') === Symbol('foo') returns false.

Ref: https://bit.ly/323Y0P6

 

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