storybook/lib/book.js

class Book {
    constructor(title, pages) {
        this.title = title;
        this.pages = pages;
    }

    displayPage(pageIndex) {
        var page = this.pages[pageIndex];

        document.getElementById("title").innerHTML = this.title;
        document.getElementById("pageImage").src = page.imageSRC;
        document.getElementById("pageText").innerHTML = page.text;

        var buttons = document.getElementById("buttons");

        // clear buttons
        buttons.innerHTML = "";

        for(var button of page.buttons) {
            const btn = document.createElement("button");
            btn.append(document.createTextNode(button.text));
            btn.setAttribute("onclick", "book.displayPage("+ button.pageIndex +")");
            buttons.append(btn);
        }
    }
}

class Page {
    constructor(imageSRC, text, butttons) {
        this.imageSRC = imageSRC;
        this.text = text;
        this.buttons = buttons;
    }
};

class Button {
    constructor(pageIndex, text) {
        this.pageIndex = pageIndex;
        this.text = text;
    }
}