JavaScript - Binary logarithm using bitwise operators
JavaScript Bit Manipulation: Exercise-8 with Solution
Write a JavaScript program to calculate the binary logarithm (log2n) using bitwise operators.
From handwiki.org -
Binary logarithm:
In mathematics, the binary logarithm (log2n) is the power to which the number 2 must be raised to obtain the value n. That is, for any real number x,
For example, the binary logarithm of 1 is 0, the binary logarithm of 2 is 1, the binary logarithm of 4 is 2, and the binary logarithm of 32 is 5.
The binary logarithm is the logarithm to the base 2 and is the inverse function of the power of two function. As well as log2, an alternative notation for the binary logarithm is lb (the notation preferred by ISO 31-11 and ISO 80000-2).
Test Data:
(1) -> 0
(2) -> 1
(4) -> 2
(32) -> 5
Sample Solution:
JavaScript Code:
const log_Two = (n) => {
if (typeof n!= "number") {
return 'It must be number!'
}
let result = 0
while (n >> 1) {
n >>= 1
result++
}
return result
}
console.log(log_Two(1))
console.log(log_Two(2))
console.log(log_Two(4))
console.log(log_Two(32))
Sample Output:
0 1 2 5
Flowchart:

Live Demo:
See the Pen javascript-bit-manipulation-exercise-8 by w3resource (@w3resource) on CodePen.
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JavaScript: Tips of the Day
Returns the symmetric difference between two arrays, after applying the provided function to each array element of both
Example:
const tips_symmetricDifference = (x, y, fn) => { const sA = new Set(x.map(v => fn(v))), sB = new Set(y.map(v => fn(v))); return [...x.filter(x => !sB.has(fn(x))), ...y.filter(x => !sA.has(fn(x)))]; }; console.log(tips_symmetricDifference([3.5, 5.5], [5.5, 7.5], Math.floor));
Output:
[3.5, 7.5]
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