# How to multiply all numbers in an array using JavaScript

## 📋 Table Of Content

In this article, we will see how to multiply all the numbers in an array using JavaScript.

Let's say we have an array of numbers like this,

``````[2,2,3,4]
``````

And we have to multiply all the numbers and give us the product as the return value.

So the output should be:

``````Input: [2,2,3,4]
Output : 2*2*3*4 = 48
``````

So using JavaScript, we will find the product of all the elements of an array using:

1. for loop or
2. Array.reduce() function.

Let's see each with an example.

## Multiple numbers in an array using for loop

We can use the `for` loop in JavaScript to find the product of all the numbers in an array.

Example:

``````const arr = [2,2,3,4]

const multiply = (arr) => {
var pro = 1;
for (i = 0; i < arr.length; i++)
pro = pro * arr[i];
return pro;
}

console.log(multiply(arr)) // Output : 48
``````

Here, in the above code, we have created a function called `multiply`, which takes an array as an argument.

And the function uses `for` loop to loop through each element in the array until the condition `i < arr.length` is met.

On each iteration of the loop, the multiplied value is stored in the variable pro . And the initial value of pro is 1 , as any number multiple with 0 is 0.

Once, the condition is met(i.e false) it returns us the product of the multiplied numbers.

## Multiply all the numbers in an array using reduce()

The reduce() method runs a user-defined "reducer" callback function on each element of an array. It returns a single value after running the callback function on each element of the array.

Syntax:

``````reduce(callbackFn, initialValue)
``````

callBackFn: The user-specified "reducer" function.

initialValue: It is the value that is passed to the function as the initial value.

So, let's use the `Array.reduce()` method to multiple numbers in an array.

``````const arr = [2,2,3,4]
const pro = arr.reduce((a, b)=> a*b, 1)

console.log(pro) // 48
``````

Here, the initialValue is 1 and not 0, because any number multiple with 0 is 0.

And, `(a, b) => a*b` is the callback function.