Summing properties from a list of objects in JS

Let's assume that we have an array of objects called products with the following structure:

let products = [
  {
     "name": "Item 1",
     "price": 20,
     "vat": 4
  },
  {
     "name": "Item 2",
     "price": 40,
     "vat": 10
  }
]

-------- APPROACH 2025 -------------

You can simply use the array functionality reduce. Basically the reducer function receives 2 parameters:

acc: it's the result of the past iterations
cur: The current iteration of the array

Also you can notice we have a 0 value as second option, this is the initialValue of acc.

products.reduce((acc, cur) => (cur.price + cur.vat) + acc, 0)

-------- APPROACH 2021 -------------
So, if we want to sum all numbers (price+vat) let's make the following steps:

1-We call the map() function to generate an array with the numeric values that we want to sum:

products.map(
  product => ([product.vat, product.price])
)
// result: [[20, 4], [40, 10]]

2-We flatten the list with the method flat():

.flat()
// result: [20, 4, 40, 10]

3-We sum all values with the reduce() method:

.reduce((a, b) => a + b)
// result: 74

In the end we get this code:

let total = products.map(product =>([product.vat,product.price])).flat().reduce((a, b) => a + b)

Thank you!