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JavaScript: Rearrange a string to become a palindrome

JavaScript String: Exercise-57 with Solution

When a word, phrase, or sequence can be read both forward and backward, it is considered a palindrome. e.g., madam or nurses run.
Write a JavaScript function that receives a string and determine whether or not it can be rearranged to become a palindrome.
Test Data:
("maamd") -> true
("civic") -> true
("IO") -> false
(12321) -> "It must be a string."

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript function to rearrange a string to become a palindrome</title>
</head>
<body>

</body>
</html>

JavaScript Code:

const test = (word) => {
    if (word.length === 0) 
    {
    return 'String should not be empty!'
   }
    if (typeof word !== 'string')
     {
       return 'It must be a string.'
     }
   const char_ctr = [...word].reduce((obj, el) => {
    obj[el] = obj[el] ? obj[el] + 1 : 1
    return obj
  }, {})
  return Object.values(char_ctr).filter(count => count % 2 !== 0).length <= 1
}
console.log(test("maamd"))
console.log(test("civic"))
console.log(test("IO"))
console.log(test(12321))

Sample Output:

true
true
false
It must be a string.

Flowchart:

Flowchart: JavaScript: Rearrange a string to become a palindrome

Live Demo:

See the Pen javascript-string-exercise-57 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