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Even or Odd (8kyu) [JavaScript]

This is a very popular kata. Let's solve it!

Chek kata on Codewars


Create a function (or write a script in Shell) that takes an integer as an argument and returns "Even" for even numbers or "Odd" for odd numbers.

Let's use Remainder (%) operator. It returns the remainder left over when one operand is divided by a second operand. It always takes the sign of the dividend.

4 % 2 // 0
3 % 2 // 1

If the number is even it returns 0 and if the number is odd it returns 1. Which converts to false or true accordingly.

const even_or_odd = num => num % 2 ? "Odd" : "Even"

Let's check others solutions.

Some people prefer to use the bitwise AND operator insted. Basicly solution is the same.

var even_or_odd = n => n & 1 ? 'Odd' : 'Even'

Math.abs() is another flavor of the same idea.

function even_or_odd(number) {
  return Math.abs(number) % 2 === 1 ? "Odd" : "Even";

Alternatively, we can create an array with 'Even' and 'Odd' values and return the first or second element.

function even_or_odd(number) {
  return ["Even", "Odd"][number % 2]
© 2021, Andrew Losseff