I have an array with items. Each of these items have the following values
invoice_rows: [
{ item: '', qty: '', price: '' }
],
For each invoice item there is a row added to the array but I want to get the total cost of all these items. So let's do some math, I have the following array with data
invoice_rows: [
{ item: 'item1', qty: '4', price: '10' }
{ item: 'item2', qty: '2', price: '10' }
{ item: 'item3', qty: '5', price: '5' }
],
The total cost should be the sum of the qty * price for each row. Making the total 40 + 20 + 25 = 85. How can I do this with the reduce method?
const invoice_rows = [
{ item: 'item1', qty: '4', price: '10' },
{ item: 'item2', qty: '2', price: '10' },
{ item: 'item3', qty: '5', price: '5' },
];
const initialValue = 0;
const sumWithInitial = invoice_rows.reduce(
(previousValue, currentValue) => previousValue + currentValue.qty*currentValue.price,
initialValue
);
console.log(sumWithInitial);
Given
const invoice_rows = [
{ item: 'item1', qty: '4', price: '10' }
{ item: 'item2', qty: '2', price: '10' }
{ item: 'item3', qty: '5', price: '5' }
];
simply first calculate qty * price using map for all items, then add the subtotals:
const total = invoice_rows.map(item => item.qty * item.price).reduce((a, b) => a + b, 0);
note that JS will implicitly cast '4' * '10' to the the number 40.
You can do:
const invoice_rows = [
{ item: 'item1', qty: '4', price: '10' },
{ item: 'item2', qty: '2', price: '10' },
{ item: 'item3', qty: '5', price: '5' }
]
const result = invoice_rows.reduce((a, { qty, price }) => a + qty * price, 0)
console.log(result)