In JavaScript, determining whether a number is even or odd is a simple task that can be accomplished with a few lines of code. In this Answer, we will explore the different methods available for checking whether a number is even or odd in JavaScript.

The modulus operator (%) is used to obtain the remainder when one number is divided by another. This operator can be used to determine whether a number is odd or even by determining whether the remainder after dividing it by two equals zero or not. It is even if it equals 0. Otherwise, it is odd.

//check if the number is evenfunction isEven (number) {return number % 2 === 0;}//check if the number is oddfunction isOdd (number) {return number % 2 !== 0;}//testconsole.log(isEven(5)); //falseconsole.log(isEven(4)); //trueconsole.log(isOdd(5)); //trueconsole.log(isOdd(4)); //false

In the code above, the `isEven()`

function checks whether a `number`

is even by using the modulus operator to check whether the remainder of dividing the `number`

by `2`

is equal to `0`

(zero).

The `isOdd()`

function checks whether a number is odd by using the modulus operator to check whether the remainder of dividing the `number`

by `2`

is not equal to `0`

(zero).

Another way to determine whether a number is even or odd is by using the bitwise AND operator (&). When this operator is applied to a `number`

and `1`

, the result is `0`

if the `number`

is even and `1`

if the `number`

is odd.

//check if the number is evenfunction isEven (number) {return (number & 1) === 0;}//check if the number is oddfunction isOdd (number) {return (number & 1) === 1;}//Testconsole.log(isEven(5)); //falseconsole.log(isEven(4)); //trueconsole.log(isOdd(5)); //trueconsole.log(isOdd(4)); //false

In the code above, the `isEven()`

function uses the bitwise AND operator to check whether the last bit of the `number`

is 0, which indicates that the `number`

is even.

The `isOdd()`

function uses the bitwise AND operator to check whether the last bit of the `number`

is 1, which indicates that the `number`

is odd.

A third way to determine whether a number is even or odd is by using the `Math.floor()`

function and division (`/`

). If we divide a `number`

by 2 and then take the floor of the result, we get the integer part of the result. If the integer part is the same as the original number, then the number is even. Otherwise, it is odd.

function isEven (number) {return Math.floor(number / 2) * 2 === number;}function isOdd (number) {return Math.floor(number / 2) * 2 !== number;}//Testconsole.log(isEven(5)); //falseconsole.log(isEven(4)); //trueconsole.log(isOdd(5)); //trueconsole.log(isOdd(4)); //false

In the above code, the `isEven()`

function divides the `number`

by `2`

, takes the floor of the result, and then multiplies the result by `2`

to check whether it is equal to the original `number`

. If it is, then the `number`

is even.

The `isOdd()`

function uses the same method but checks whether the result is not equal to the original number, which indicates that the `number`

is odd.

In this Answer, we have explored different methods for checking whether a number is even or odd in JavaScript. Since each approach has its own advantages and disadvantages, you can make a decision based on the specific requirements of your project.

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