функция фильтра не возвращает пользовательское значение, вам нужно использовать map and filter
вместе или альтернативно reduce
var products = [
{name: 'A', quantity: 2, unitPrice: 100, category: 'Electronic goods'},
{name: 'B', quantity: 1, unitPrice: 400, category: 'Electronic goods'},
{name: 'C', quantity: 5, unitPrice: 15, category: 'Clothing goods'},
{name: 'D', quantity: 2, unitPrice: 95, category: 'Clothing goods'},
{name: 'E', quantity: 300, unitPrice: 10, category: 'Home, Garden goods'},
{name: 'F', quantity: 60, unitPrice: 150, category: 'Handmade'},
{name: 'G', quantity: 10, unitPrice: 105, category: 'Automotive goods'}
];
var bigPrice = products.map(function(item) {
if (item.quantity * item.unitPrice > 1000) {
return item.name + ' || ' + item.category;
}
}).filter(item => typeof item !== 'undefined');
console.log(bigPrice)
или
var products = [
{name: 'A', quantity: 2, unitPrice: 100, category: 'Electronic goods'},
{name: 'B', quantity: 1, unitPrice: 400, category: 'Electronic goods'},
{name: 'C', quantity: 5, unitPrice: 15, category: 'Clothing goods'},
{name: 'D', quantity: 2, unitPrice: 95, category: 'Clothing goods'},
{name: 'E', quantity: 300, unitPrice: 10, category: 'Home, Garden goods'},
{name: 'F', quantity: 60, unitPrice: 150, category: 'Handmade'},
{name: 'G', quantity: 10, unitPrice: 105, category: 'Automotive goods'}
];
var bigPrice = products.filter(function(item) {
return (item.quantity * item.unitPrice) > 1000
}).map(item => item.name + ' || ' + item.category);
console.log(bigPrice)