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:

- for loop or
- 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.