task.js

'use strict'
//Задача 2.3.1
class PrintEditionItem {
	constructor(name, releaseDate, pagesCount) {
		this.name = name;
		this.releaseDate = releaseDate;
		this.pagesCount = pagesCount;
		this.state = 100;
		this.type = null;
	}

	fix(){
		this.state *= 1.5
	};

	set state(number) {
		if (number < 0) {
			this._state = 0
		} else if (number > 100) {
			this._state = 100
		} else {
			this._state = number;
		}
	}

	get state() {
		return this._state;
	}
}

class Magazine extends PrintEditionItem {
	constructor(name, releaseDate, pagesCount) {
		super(name, releaseDate, pagesCount);
		this.type = "magazine";
	}
}
class Book extends PrintEditionItem {
	constructor(author,name, releaseDate, pagesCount) {
		super(name, releaseDate, pagesCount);
		this.type = "book";
		this.author = author;
	}
}

class NovelBook extends Book{
	constructor(name, releaseDate, pagesCount) {
		super(name, releaseDate, pagesCount);
		this.type = "novel";
	}
}

class FantasticBook extends Book{
	constructor(name, releaseDate, pagesCount) {
		super(name, releaseDate, pagesCount);
		this.type = "fantastic";
	}
}

class DetectiveBook extends Book{
	constructor(name, releaseDate, pagesCount) {
		super(name, releaseDate, pagesCount);
		this.type = "detective";
	}
}

//Задача 2.3.2
class Library {
	constructor(name, books) {
		this.name = name;
		this.books = [];
	};

	addBook(book) {
		if (book.state > 30) {
			this.books.push(book);
		}
	};

	findBookBy(type, value){
		for (let i = 0; i < this.books.length; i++){
			if (this.books[i][type] === value)
				return this.books[i];
		}
		return null
	};

	giveBookByName(bookName){
		for (let i = 0; i < this.books.length; i++){
			const item = this.books.findIndex(book => book.name === bookName);
			if (item != -1)
				return this.books.splice(item, 1)[0];
		}
		return null
	};
}

//Задача 2.3.3
class StudentLog {
	constructor(name) {
		this.name = name;
		this.grades = {};
	}

	getName() {
		return this.name;
	}

	addGrade(grade, subject) {
		if (grade < 1 || grade > 5 || typeof grade !== 'number') {
			return `Вы пытались поставить оценку "${grade}" по предмету "${subject}". Допускаются только числа от 1 до 5.`
		} else if (this.grades[subject]) {
			this.grades[subject].push(grade);
			return this.grades[subject].length;
		}else {
			this.grades[subject] = [grade];
			return 1;
		}
	}

	getAverageBySubject(subject) {
		if (Object.keys(this.grades).includes(subject)) {  //если обьект grades включает в себя subject
			let sum = 0;
			for (let rating of this.grades[subject]) {
				sum += rating;
			}
			return sum / this.grades[subject].length;
		} else {
			return 0;
		}
	}

	getTotalAverage() {
		let totalAverage = 0;
		for (let element in this.grades) {
			totalAverage += this.getAverageBySubject(element);
		}
		totalAverage = totalAverage / Object.keys(this.grades).length;
		return totalAverage;
	}
}