To find the sum of an array of numbers in JavaScript, you can use the `reduce()`

method. The `reduce()`

method allows you to apply a function to each element in the array, reducing the array to a single value.

Here’s an example of how you can use the `reduce()`

method to find the sum of an array of numbers:

```
const numbers = [1, 2, 3, 4, 5];
const sum = numbers.reduce((total, current) => total + current, 0);
console.log(sum); // Output: 15
```

In this example, the `reduce()`

method iterates over the `numbers`

array and applies the function to each element. The function takes two arguments: `total`

and `current`

. `total`

is the accumulated value, and `current`

is the current element being processed. The function adds `total`

and `current`

together and returns the result, which is then passed to the next iteration as the new value of `total`

.

The `reduce()`

method also takes an optional second argument, which is the initial value of the `total`

argument. In this example, we pass `0`

as the initial value, so the first iteration will use `0`

as the value of `total`

and `1`

as the value of `current`

.

You can also use the `for`

loop to find the sum of an array of numbers:

```
const numbers = [1, 2, 3, 4, 5];
let sum = 0;
for (let i = 0; i < numbers.length; i++) {
sum += numbers[i];
}
console.log(sum); // Output: 15
```

This loop iterates over the `numbers`

array and adds each element to the `sum`

variable. At the end of the loop, `sum`

will contain the sum of all the elements in the `numbers`

array.