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JavaScript - Next power of two of a given number

JavaScript Bit Manipulation: Exercise-4 with Solution

Write a JavaScript program to find next power of two of a given number.

A power of two is a number of the form 2n where n is an integer, that is, the result of exponentiation with number two as the base and integer n as the exponent.
The first ten powers of 2 for non-negative values of n are: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, ...

Test Data:
(1) -> 1
(4) -> 4
(9) -> 16
("15") -> "It must be number!"

Sample Solution:

JavaScript Code:

const next_Power_Of_Two = (num) => {
      if (typeof num != "number") {
          return 'It must be number!'
      }

  if (num > 0 && (num & (num - 1)) === 0) 
    return num
  let result = 1

  while (num > 0) 
  {
    result = result << 1
    num = num >> 1
  }
  return result
}
console.log(next_Power_Of_Two(1))
console.log(next_Power_Of_Two(4))
console.log(next_Power_Of_Two(9))
console.log(next_Power_Of_Two("15"))

Sample Output:

1
4
16
It must be number!

Flowchart:

Flowchart: JavaScript - Next power of two of a given number.

Live Demo:

See the Pen javascript-bit-manipulation-exercise-4 by w3resource (@w3resource) on CodePen.


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

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Previous: Number of 0 bits in a binary representation.
Next: Odd or even number using bit manipulation.

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JavaScript: Tips of the Day

Creates an object composed of the properties the given function returns truthy for. The function is invoked with two arguments: (value, key)

Example:

const tips_composed = (obj, fn) =>
  Object.keys(obj)
    .filter(k => fn(obj[k], k))
    .reduce((acc, key) => ((acc[key] = obj[key]), acc), {});

console.log(tips_composed({ p: 2, q: '4', r: 6 }, x => typeof x === 'number'));

Output:

[object Object] {
  p: 2,
  r: 6
}