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JavaScript - Swap two bits at given position in an integer

JavaScript Bit Manipulation: Exercise-7 with Solution

Write a JavaScript program to swap two bits (from the right side, rightmost position is 0) in the binary representation of an integer at the given positions.

Test Data:
(245) -> 249

Explanation:
245 -> 11110101
Swap the 1st and 4th bits from the side of the said binary number.
11100111 -> 231
(137) -> 73
Explanation:
137 -> 10001001
Swap the 6th and 7th bits from the side of the said binary number.
01001001 -> 73

Sample Solution:

JavaScript Code:

const swap_bits = (n, pos1, pos2) => {
   if (typeof n!= "number") {
          return 'It must be number!'
      }
   if ((((n & (1 << pos1)) >> pos1) ^ ((n & (1 << pos2)) >> pos2)) == 1)
        {
            n ^= (1 << pos1);
            n ^= (1 << pos2);
        }
   return n;
}
console.log(swap_bits(245,1,4))
console.log(swap_bits(137,6,7))
console.log(swap_bits("16"))

Sample Output:

231
73
It must be number!

Flowchart:

Flowchart: JavaScript - Swap two bits at given position in an integer.

Live Demo:

See the Pen javascript-bit-manipulation-exercise-7 by w3resource (@w3resource) on CodePen.


* To run the code mouse over on Result panel and click on 'RERUN' button.*

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Previous: Check a number is a power of 4 or not.
Next: Binary logarithm using bitwise operators.

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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