ArrayEvery.js

let data  = [
    {id: 1, title: 'Nite watch', price: 33, discount:0},
    {id: 2,  title: 'what I want', price: 12, discount:0.4},
    {id: 3, title: 'Mercy at last', price: 405, discount:0.25},
    {id: 4, title: 'Nothting between', price: 550, discount:0}
];
let discountedBooks = data.every(item => item.discount > 0 );
console.log(discountedBooks);

// result

false
}