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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 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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JavaScript: Tips of the Day

function and arguments

const person = {
  name: 'Lydia Hallie',
  hobbies: ['coding'],
};

function addHobby(hobby, hobbies = person.hobbies) {
  hobbies.push(hobby);
  return hobbies;
}

addHobby('running', []);
addHobby('dancing');
addHobby('baking', person.hobbies);

console.log(person.hobbies);

The addHobby function receives two arguments, hobby and hobbies with the default value of the hobbies array on the person object.
First, we invoke the addHobby function, and pass "running" as the value for hobby and an empty array as the value for hobbies. Since we pass an empty array as the value for y, "running" gets added to this empty array.
Then, we invoke the addHobby function, and pass "dancing" as the value for hobby. We didn't pass a value for hobbies, so it gets the default value, the hobbies property on the person object. We push the hobby dancing to the person.hobbies array.
Last, we invoke the addHobby function, and pass "bdaking" as the value for hobby, and the person.hobbies array as the value for hobbies. We push the hobby baking to the person.hobbies array.
After pushing dancing and baking, the value of person.hobbies is ["coding", "dancing", "baking"]

Ref: https://bit.ly/2Hcpkm6