JavaScript: Test if a number is a power of 2

JavaScript Math: Exercise-13 with Solution

Write a JavaScript function to test if a number is a power of 2.

Test Data:
console.log(power_of_2(16));
console.log(power_of_2(18));
console.log(power_of_2(256));
Output:
true
false
true

Pictorial Presentation:

Sample Solution-1:

JavaScript Code:

function power_of_2(n) {
 if (typeof n !== 'number') 
      return 'Not a number'; 

    return n && (n & (n - 1)) === 0;
}

console.log(power_of_2(16));
console.log(power_of_2(18));
console.log(power_of_2(256));

Sample Output:

true
false
true

Flowchart:

Sample Solution-2:

JavaScript Code:

const power_of_2 = n => !!n && (n & (n - 1)) == 0;
console.log(power_of_2(16));
console.log(power_of_2(18));
console.log(power_of_2(256)); 

Sample Output:

true
false
true

Live Demo:

See the Pen javascript-math-exercise-13 by w3resource (@w3resource) on CodePen.

Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript function to find out if a number is a natural number or not.
Next: Write a JavaScript function to round a number to a given decimal places.