books/client/view/page.js

const frappe = require('frappe-core');

class Page {
    constructor(title) {
        this.handlers = {};
        this.title = title;
        this.make();
    }

    make() {
        this.body = frappe.ui.add('div', 'page hide', frappe.desk.main);
    }

    hide() {
        frappe.ui.add_class(this.body, 'hide');

        this.trigger('hide');
    }

    show(params) {
        if (frappe.router.current_page) {
            frappe.router.current_page.hide();
        }
        frappe.ui.remove_class(this.body, 'hide');
        frappe.router.current_page = this;
        document.title = this.title;

        this.trigger('show', params);
    }

    on(event, fn) {
        if (!this.handlers[event]) this.handlers.event = [];
        this.handlers[event].push(fn);
    }

    trigger(event, params) {
        if (this.handlers[event]) {
            for (let handler of this.handlers[event]) {
                handler(params);
            }
        }
    }
}

module.exports = { Page: Page };