JavaScript Program to Check if a Number is Odd or Even

In this article, we are going to learn how to check whether the number is Even or Odd using JavaScript. In the number system any natural number that can be expressed in the form of (2n + 1) is called an odd number and if the number can be expressed in the form of 2n is called an even number.

In other words, Those numbers that are completely divisible by 2 (give the remainder 0 after dividing by 2) are known as even numbers and those which divided by 2 and leave a reminder 1 are called odd numbers.

Even = {2k : k ∈ Z}
Odd = {2k + 1 : k ∈  Z}
where k is an integer. 

Example:

Input: 2
Output: Even number
Input: 41
Output: Odd Number

There are several methods that can be used to Check if a Number is Odd or Even, which are listed below:

Approach 1: Using the modulo Operator

In this method, we use the JavaScript Modulo Operator (%) to check whether the number is even or odd in JavaScript. We will evaluate the N % 2, and if the result is 0 then the number is even otherwise the number is odd.

Syntax:

remainder = var1 % var2

Example: In this example, we are using the modulo operator to find given number is even or odd.

Javascript

// Returns true if n is
// even, else odd
function isEven(n) {
    return (n % 2 == 0);
}

// Driver code
let n = 101;

isEven(n) ? console.log("Even") : console.log("Odd");

Output

Odd

Approach 2: Using Bitwise & Operator

A better solution is to use bitwise operators. We need to check whether the last bit is 1 or not. If the last bit is 1 then the number is odd, otherwise the number is even.

Syntax:

a & b

Example: In this example, we are using the bitwise & operator to find given number is even or odd.

Javascript

function checkOddOrEven(n) {
    if (n & 1 == 1) {
        return "Number is odd";
    }
    return "Number is even";
}

console.log(checkOddOrEven(12));
console.log(checkOddOrEven(121));

Output

Number is even
Number is odd

Approach 3: Using Bitwise OR Operator (|)

JavaScript Bitwise OR(|) Operator is used to compare two operands by performing OR operation on individual bits of the operands and returns true even if one of the compared bits is 1.

Syntax:

a | b

Example: In this example, we are using the bitwise OR operator to find whether our given number is even or odd.

Javascript

function checkOddOrEven(number) {
    return (number | 1) === number ? 'Odd' : 'Even';
}

console.log(checkOddOrEven(14));
console.log(checkOddOrEven(17));

Output

Even
Odd

Approach 4: Using Ternary Operator

Ternary operator (?:) is a shorthand conditional operator that evaluates a condition and returns one of two expressions based on the result.

Syntax:

condition ? value if true : value if false

Example: In this example, we are using the Ternary operator to find given number is even or odd.

Javascript

function checkOddOrEven(num) {
    return num % 2 === 0 ? 'Even' : 'Odd';
}

console.log(checkOddOrEven(21));
console.log(checkOddOrEven(12));

Output

Odd
Even