How to find the sum of numbers in an array javascript

In this tutorial we are going to learn two ways to find the sum of an array of numbers by using JavaScript.

First way using for of loop.

let arr = [1,2,3,4,5];

let sum = 0;

for (let num of arr){

    sum = sum + num
}

console.log(sum) // 15

In the above code, we used for of loop to get the number directly instead of index.

On each iteration, we have added the number to sum variable.

Array.reduce( ) method

There is an inbuilt reduce method in JavaScript which helps to calculate the sum of numbers in the array.

let arr = [1,2,3,4,5];

const sum =  arr.reduce((result,number)=> result+number);

console.log(sum) // 15

In the above code on each iteration reducer function store, the numbers sum inside the result parameter and finally returns the result value.

reduce() method takes the callback function as its first argument and runs that callback function on each element present in the array.

The callback function takes two parameters result and current element.