Cart API

APIService

;window.APIService = (function(_){
    function ajax(headers, url, method, data, onsuccess, onerror) {
        var request = new XMLHttpRequest();
        request.open(method, url, true);
        _.forEach(headers, function(v, k){
            request.setRequestHeader(k, v);
        });
        request.onsuccess = onsuccess || function(){};
        request.onerror = onerror || function(){};
        request.onload = function() {
            try {
                var data = JSON.parse(request.responseText);
            } catch (e){
                return this.onerror({
                    success: false,
                    error: e.message
                });
            }
            if (request.status >= 200 && request.status < 400) {
                this.onsuccess(data);
            } else {
                this.onerror(data);
            }
        };
        request.send(JSON.stringify(data));
        return request;
    }
    function APIService(options){
        Object.assign(this, options);
        this.ajax = ajax.bind(this, this.headers, this.url);
        this.get = this.ajax.bind(this, 'GET');
        this.post = this.ajax.bind(this, 'POST');
    }
    return APIService;
}(_));

Cart.js

;window.Cart = (function(){
    /**
     * @typedef Cart
     * @property {Number} items
     * @property {Number} sum
     * @property {Number} oldSum
     * @property {Number} weight
     * @property {Number} discount
     */
    var defaultCart = {
        items: 0,
        sum: 0,
        oldSum: 0,
        weight: 0,
        discount: 0
    };

    /**
     * @returns {Cart}
     * @constructor
     */
    function Cart(cart){
        Object.assign(this, cart);
    }
    Object.assign(Cart.prototype, defaultCart);

    return Cart;
}());

CartService

;window.CartService = (function(APIService, CONSTANTS, Cart, errorHandler){
    var cart = new Cart();
    var loaded = false;
    function CartService(){
        this.url = CONSTANTS.CART.URL;
        this.headers = {
            'Content-Type': 'application/json'
        };
        APIService.apply(this, arguments);
    }
    Object.assign(CartService.prototype, APIService.prototype, CartService);
    Object.defineProperty(CartService.prototype, 'data', {
        get: function(){
            var req = {
                method: 'getFullCart'
            };
            if(!loaded){
                return this.post(req, function(res){
                    loaded = res.success;
                    cart = new Cart(res.data);
                    return cart;
                }, function(res){
                    errorHandler(res.error);
                });
            }
            return cart;
        },
        set: function(data){
            var req = Object.assign({"method": "addToCart"}, data);
            // return this.post(req, function(res){
            //     if (res.success) {
            cart = new Cart(data);
            return cart;
            //     }
            // });
        }
    });
    CartService.prototype.addToCart = function(product){
        var req = Object.assign({"method": "addToCart"}, product);
        return this.post(req, function(res){
            if (res.success) {
                cart.products = new Cart(data);
            }
        });
    }
    return CartService;
}(window.APIService, window.API, window.Cart, console.error));