Better way to sum a property value in an array

Question

I have something like this:

$scope.traveler = [
            {  description: \'Senior\', Amount: 50},
            {  description: \'Senior\', Amount: 50},
             


        

Answer 1

You can do the following:

$scope.traveler.map(o=>o.Amount).reduce((a,c)=>a+c);

Answer 2

It's working for me in TypeScript and JavaScript:

let lst = [
     { description:'Senior', price: 10},
     { description:'Adult', price: 20},
     { description:'Child', price: 30}
];
let sum = lst.map(o => o.price).reduce((a, c) => { return a + c });
console.log(sum);

I hope is useful.

Answer 3

I always avoid changing prototype method and adding library so this is my solution:

Using reduce Array prototype method is sufficient

// + operator for casting to Number
items.reduce((a, b) => +a + +b.price, 0);

Answer 4

can also use Array.prototype.forEach()

let totalAmount = 0;
$scope.traveler.forEach( data => totalAmount = totalAmount + data.Amount);
return totalAmount;