JavaScript - Position of the rightmost set bit of a number

JavaScript Bit Manipulation: Exercise-12 with Solution

Rightmost Set Bit

Write a JavaScript program to find the position of the rightmost set bit of a given number. The number 1 represents the set bits in a binary number.

Test Data:
(34) -> 2
Explanation:
34 in binary is 100010
Set bits in the 2^nd position of the said binary format.
(104) -> 4
Explanation:
104 in binary is 1101000
Set bits in the 4^th position of the said binary format.

Sample Solution:

JavaScript Code:

// Define a function to find the position of the rightmost set bit in a number
const turn_On_Kth_Bit = (n, k) => {
  // Check if the input is not a number
  if (typeof n != "number") {
    return 'It must be number!'; // Return an error message
  }
  // Check if the rightmost bit is already set
  if ((n & 1) != 0) {
    return 1; // Return the position 1
  }
  // Find the position of the rightmost set bit
  n = n ^ (n & (n - 1)); // Remove all bits except the rightmost set bit
  let pos = 0; // Initialize the position variable
  while (n != 0) {
    n = n >> 1; // Right shift n by 1 bit
    pos++; // Increment the position
  }
  return pos; // Return the position of the rightmost set bit
}

// Initialize variable n with a value
let n = 34;

// Display the binary representation of n
console.log(n + " in binary is " + n.toString(2));

// Call the turn_On_Kth_Bit function to find the position of the rightmost set bit
let position = turn_On_Kth_Bit(n);

// Display the position of the rightmost set bit
console.log("Position of the rightmost set bit of the said number: " + position);

// Update variable n with a new value
n = 104;

// Display the binary representation of n
console.log(n + " in binary is " + n.toString(2));

// Call the turn_On_Kth_Bit function to find the position of the rightmost set bit
position = turn_On_Kth_Bit(n);

// Display the position of the rightmost set bit
console.log("Position of the rightmost set bit of the said number: " + position);

Output:

34 in binary is 100010
Position of the rightmost set bit of the said number: 2
104 in binary is 1101000
Position of the rightmost set bit of the said number: 4

Flowchart:

Live Demo:

See the Pen javascript-bit-manipulation-exercise-12 by w3resource (@w3resource) on CodePen.

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

For more Practice: Solve these Related Problems:

• Write a JavaScript function that finds the position of the rightmost set bit (1) in a given integer using bitwise operations.
• Write a JavaScript function that uses a loop to shift the number right until the least significant bit is 1.
• Write a JavaScript function that validates the input and returns an appropriate message for zero input.
• Write a JavaScript function that returns the position (starting at 1) of the rightmost set bit for a non-zero number.

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