I need some code that implements calculating the average price of books, type of ROMAN. The type field can be written in any case (roman, ROMAN).
let books = [
{ name: 'Some-1', author: 'Puskin', type: 'roman', price: 204.5 },
{ name: 'Some-2', author: 'Tolstoy', type: 'ROMAN', price: 321.0 },
{ name: 'Some-3', author: 'Pero', type: 'tale', price: 211.0 },
{ name: 'Some-4', author: 'Koelyo', type: 'roman', price: 204.5 },
{ name: 'Some-5', author: 'Christie', type: 'Roman', price: 245.5 },
{ name: 'Some-6', author: 'Hohol', type: 'tale', price: 366.0 }
];
So I derived all types with this method:
const getType = books.map(({type}) => type.toLowerCase())
And further my problem is that I don't know how got access to price
You can do that in several Method
You can loop trough the array and sum up all the prices there and then devide on its length, also you will check if the current object type equals roman, by using .toLowerCase()
if you want to return the natural number you can use .toFixed() method
let books = [
{ name: 'Some-1', author: 'Puskin', type: 'roman', price: 204.5 },
{ name: 'Some-2', author: 'Tolstoy', type: 'ROMAN', price: 321.0 },
{ name: 'Some-3', author: 'Pero', type: 'tale', price: 211.0 },
{ name: 'Some-4', author: 'Koelyo', type: 'roman', price: 204.5 },
{ name: 'Some-5', author: 'Christie', type: 'Roman', price: 245.5 },
{ name: 'Some-6', author: 'Hoho', type: 'tale', price: 366.0 }
]
let TotalPrice = 0;
let romanPriceLength = 0;
for (let i = 0; i < books.length; i++) {
if ((books[i].type).toLowerCase() === "roman") {
TotalPrice += books[i].price
romanPriceLength++
}
}
console.log(TotalPrice / romanPriceLength)
console.log((TotalPrice / romanPriceLength).toFixed(0))let books = [
{ name: 'Some-1', author: 'Puskin', type: 'roman', price: 204.5 },
{ name: 'Some-2', author: 'Tolstoy', type: 'ROMAN', price: 321.0 },
{ name: 'Some-3', author: 'Pero', type: 'tale', price: 211.0 },
{ name: 'Some-4', author: 'Koelyo', type: 'roman', price: 204.5 },
{ name: 'Some-5', author: 'Christie', type: 'Roman', price: 245.5 },
{ name: 'Some-6', author: 'Hoho', type: 'tale', price: 366.0 }
]
let TotalPrice = 0;
let romanPriceLength = 0;
books.forEach(book => {
if((book.type).toLowerCase() === "roman"){
TotalPrice += book.price
romanPriceLength ++
}
})
console.log(TotalPrice / romanPriceLength)
console.log((TotalPrice / romanPriceLength ).toFixed(0))let books = [
{ name: 'Some-1', author: 'Puskin', type: 'roman', price: 204.5 },
{ name: 'Some-2', author: 'Tolstoy', type: 'ROMAN', price: 321.0 },
{ name: 'Some-3', author: 'Pero', type: 'tale', price: 211.0 },
{ name: 'Some-4', author: 'Koelyo', type: 'roman', price: 204.5 },
{ name: 'Some-5', author: 'Christie', type: 'Roman', price: 245.5 },
{ name: 'Some-6', author: 'Hoho', type: 'tale', price: 366.0 }
]
let romanPriceLength = 0;
let TotalPrice = 0;
for(let book of books){
if(book.type.toLowerCase() === "roman"){
TotalPrice += book.price
romanPriceLength++
}
}
console.log(TotalPrice / romanPriceLength)
console.log((TotalPrice / romanPriceLength).toFixed(0))You can do it with filter and reduce too :
let books = [
{ name: 'Some-1', author: 'Puskin', type: 'roman', price: 204.5 },
{ name: 'Some-2', author: 'Tolstoy', type: 'ROMAN', price: 321.0 },
{ name: 'Some-3', author: 'Pero', type: 'tale', price: 211.0 },
{ name: 'Some-4', author: 'Koelyo', type: 'roman', price: 204.5 },
{ name: 'Some-5', author: 'Christie', type: 'Roman', price: 245.5 },
{ name: 'Some-6', author: 'Hoho', type: 'tale', price: 366.0 }
]
const romans = books.filter(book => book.type.toLowerCase() == 'roman')
const romansTotalPrice = romans.reduce((a, {price}) => a + price, 0)
const romansAvaragePrice = (romansTotalPrice / romans.length).toFixed(2);
console.log(romansAvaragePrice)Use a for loop or forEach() to get the sum of prices and the count.
let books = [
{ name: 'Some-1', author: 'Puskin', type: 'roman', price: 204.5 },
{ name: 'Some-2', author: 'Tolstoy', type: 'ROMAN', price: 321.0 },
{ name: 'Some-3', author: 'Pero', type: 'tale', price: 211.0 },
{ name: 'Some-4', author: 'Koelyo', type: 'roman', price: 204.5 },
{ name: 'Some-5', author: 'Christie', type: 'Roman', price: 245.5 },
{ name: 'Some-6', author: 'Hoho', type: 'tale', price: 366.0 }
]
let TotalPrice = 0;
let count = 0;
books.forEach(book => {
if (book.type.toLowerCase() == 'roman') {
TotalPrice += book.price;
count++;
}
});
console.log((TotalPrice / books.length).toFixed(2))