Add multiple object values with the same key from object array using forEach in JavaScript

Question

I am working on a shopping basket feature using Vue JS, I need to create a subtotal feature which multiplies the price and quantity values of each item and adds them together to create a subtotal.

dataSet: [
  {
  "instock" : '',
  "price": 49,
  "qty": 1,
  "subTotal": '' 
  },
  {
  "instock" : '',
  "price": 29,
  "qty": 1,
  "subTotal" : '',
  },
]

I have managed to return the values for each of the 'price' and 'qty' using forEach on the object array like so:

getSubTotal(dataSet) {    
   this.dataSet.forEach(function(data) {
   console.log(data.price)
})
console
49
29

So far so good (I think), I am getting the price values returned to me, the only problem is that they are not being return in the same array but seperately. I really need them to be returned as [49,29] so I am able add the values together for the subtotal. I am able to hard code each array by index then add them seperately but this does not future proof the eventuality of a new clothing item in the object array.

Any advice/criticism or help would be greatly appreciated.

Answer 1

 getSubTotal(dataSet) { return this.dataSet.map(function(data) { return data.price; }) 

Answer 2

Okay so I was able to figure this out.

dataSet: [
 {
 "price": 49,
 "qty": 1,
 },
 {
 "price": 29,
 "qty": 1,
 },
]

subTotals(data) {
  const calcArray = [data.price, data.qty];
  return calcArray.reduce((a,b)=> {
    //multiply price by quantity for subtotal
    return a*b;
  });
}