javascriptecmascript-6

Can we do orders.stream().mapToInt(Order::getQuantity).sum()) in javascript?

In java I'm using streams to calculate the sum of a list of orders like this:

orders.stream().mapToInt(Order::getQuantity).sum()

I'm wondering whether there is an equally elegant way to do this in javascript when iterating over an array of Order instances. Essentially an array like this:

[{quantity: 10}, {quantity: 20}, {quantity: 15}, ...]

I have something like this so far, but I'm wondering if it could be even shorter:

  orders.map((order)=>order.quantity).reduce((a, b)=> a+b,0);
Solution

  • You do not need to use map just do:

    orders.reduce((a, b) => a + b.quantity, 0));


    console.log([{
  quantity: 10
}, {
  quantity: 20
}, {
  quantity: 15
}].reduce((a, b) => a + b.quantity, 0));