# JavaScript Program to Find Remainder of Array Multiplication Divided by n

Last Updated : 22 Feb, 2024

In JavaScript, the remainder of the array multiplication when divided by the number n can be found by iteration, functional programming or array reduction. , it’s often necessary to calculate the remainder of the product of all elements in an array when divided by a given number ‘n’. There are various possible approaches in JavaScript to achieve this which are as follows:

## Using forEach() method

This approach iterates through each element of the array using the forEach() method and calculates the remainder of the product of all elements when divided by a given number ‘n’.

The forEach() method iterates over elements of an array and executes a provided function once for each array element. It allows you to perform a specific action on each element of the array without mutating the array itself.

Example: To demonstrate finding the remainder of the array multiplication using forEach() method.

## Javascript

 `function` `findRemainder1(arr, n) {` `    ``let product = 1;` `    ``arr.forEach((num) => (product *= num));` `    ``return` `product % n;` `}`   `let arr1 = [3, 7, 2, 5];` `let n1 = 11;` `console.log(findRemainder1(arr1, n1));`

Output

```1
```

Time Complexity: O(n)

Space Complexity: O(1)

## Using reduce() function

This method uses the reduce() function to accumulate the product of all array elements and then calculates the remainder when divided by a specified number ‘n’.

The reduce() method executes a reducer function on each element of the array, resulting in a single output value. It accumulates the result of the function calls on each element, providing the final result.

Example: This example illustrates finding the remainder of the array multiplication divided by ‘n’ in JavaScript using the reduce() method.

## Javascript

 `function` `findRemainder2(arr, n) {` `    ``let product = arr.reduce((acc, val) => {` `        ``acc * val, 1` `    ``});` `    ``return` `product % n;` `}`   `let arr2 = [4, 8, 6, 2];` `let n2 = 13;` `console.log(findRemainder2(arr2, n2));`

Output

```NaN
```

Time Complexity: O(n)

Space Complexity: O(1)

## Using functional approach with reduce()

In this approach, a functional programming style is employed along with the reduce() function to find the remainder of the array multiplication when divided by a given number ‘n’.

Example: Here, the code showcases how to find the remainder of the array multiplication divided by ‘n’ in JavaScript using the reduce() method with a functional approach.

## Javascript

 `function` `findRemainder3(arr, n) {` `    ``return` `arr.reduce((acc, val) => {` `        ``(acc * val) % n, 1` `    ``});` `}`     `let arr3 = [1, 2, 3, 4];` `let n3 = 17;` `console.log(findRemainder3(arr3, n3));`

Output

```undefined
```

Time Complexity: O(n)

Space Complexity: O(1)

This approach utilizes a traditional for-loop to traverse the array and compute the product of all elements, followed by finding the remainder when divided by a provided number ‘n’.

Example: To demonstrates how to find the remainder of the array multiplication divided by ‘n’ in JavaScript using a for loop.

## Javascript

 `function` `findRemainder4(arr, n) {` `    ``let product = 1;` `    ``for` `(let num of arr) {` `        ``product *= num;` `        ``product %= n;` `    ``}` `    ``return` `product;` `}`   `let arr4 = [2, 4, 6, 8];` `let n4 = 19;` `console.log(findRemainder4(arr4, n4));`

Output

```4
```

Time Complexity: O(n)

Space Complexity: O(1)

Article Tags :