how to sum up number in an array js code example

Example 1: sum of all numbers in an array javascript

const arrSum = arr => arr.reduce((a,b) => a + b, 0)

Example 2: how to add up all numbers in an array

const numbers = [10, 20, 30, 40] 
add = (a, b) =>  a + b
const sum = numbers.reduce(add)