const sum = arr => arr.reduce((a, b) => a + b, 0);
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
arr.reduce((a, b) => a + b)
arrSum = function(arr){ return arr.reduce(function(a,b){ return a + b }, 0);}
array.reduce((a, b) => a + b, 0)