Update an Array total property with multiplying the properties

Question

So I have an array and I want to change the total by multiplying value with qty( I changed it to english), I finally figured out how to get the total. And now I am stuck on updating the total in the right property.

I think a loop or something but it just does not makes sense to me yet on how I can make it clear it should update the right property with the right sum of value and qty.

I then later going to make it so that you can change it in the form and add to it, but that is a step further. I have been looking at Array Map and ForEach to change it. But I am getting a little stuck

The expected output would be:

{omschrijving:"Brood", value:1, qty:3, total:3},

{omschrijving:"Brocolli", value:0.99, qty:2, total:1.98},

{omschrijving:"Krentenbollen", value:1.20, qty:4, total:4.80},

{omschrijving:"Noten", value:2.99, qty:2, total:5.98}

Also I realize that my forEach outputs 5 numbers? :O

Also I removed my manual total from the property, because I wanted to change it.

Now it gives an error :) So I fill it in manual again.

    let product =  [
{omschrijving:"Brood", value:1, qty:3, total:},
{omschrijving:"Brocolli", value:0.99, qty:2, total:},
{omschrijving:"Krentenbollen", value:1.20, qty:4, total:},
{omschrijving:"Noten", value:2.99, qty:2, total:}
]



product.forEach(function (arrayItem) {
    var x = arrayItem.value * arrayItem.qty;
    console.log(x);
});

Answer 1

Here is a solution using simple for loop

let product =  [
{omschrijving:"Brood", value:1, qty:3},
{omschrijving:"Brocolli", value:0.99, qty:2},
{omschrijving:"Krentenbollen", value:1.20, qty:4},
{omschrijving:"Noten", value:2.99, qty:2}
]

for(let i=0;i<product.length;i++)
{
  product[i].total = product[i].value*product[i].qty;
}
console.log(product);

Using forEach method

let product =  [
    {omschrijving:"Brood", value:1, qty:3},
    {omschrijving:"Brocolli", value:0.99, qty:2},
    {omschrijving:"Krentenbollen", value:1.20, qty:4},
    {omschrijving:"Noten", value:2.99, qty:2}
    ]

product.forEach(function (arrayItem) {
        arrayItem.total = arrayItem.value * arrayItem.qty;
    });
console.log(product);

Using .map method

let product =  [
    {omschrijving:"Brood", value:1, qty:3},
    {omschrijving:"Brocolli", value:0.99, qty:2},
    {omschrijving:"Krentenbollen", value:1.20, qty:4},
    {omschrijving:"Noten", value:2.99, qty:2}
    ]

product.map(pro => 
   {pro.total = pro.value * pro.qty;
   return pro;
   }
)
console.log(product);