JAVASCRIPT

array sum javascript

const arr = [1, 2, 3, 4];
const sum = arr.reduce((a, b) => a + b, 0);
// sum = 10

summation js

const summation = (n) => (n * (n + 1)) / 2;

js sum

const array = [1, 2, 3];
const result = array.reduce((accumulator, current) => accumulator + current, 0);
// result === 1 + 2 + 3;

sum function in javascript

let sum = (...para) => para.reduce((d,b) => d + b);

js summation

const summation = n => n * (n + 1) / 2;