how to get the sum of an array in javascript code example

Example 1: array sum javascript

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

Example 2: sum of all numbers in an array javascript

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

Example 3: javascript sum array values

function getArraySum(a){
    var total=0;
    for(var i in a) { 
        total += a[i];
    }
    return total;
}

var payChecks = [123,155,134, 205, 105]; 
var weeklyPay= getArraySum(payChecks); //sums up to 722

Example 4: sum of an array

const sum = (...args) => args.reduce((a, b) => a + b, 0);
console.log(sum(1,2,3)); // returns 6

Example 5: summation js

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