Question

在这段代码中，我有一个购物车，其中包含cart.items数组中的相册对象。共有五个不同的专辑元素，但是，它们有多个实例。我试图显示专辑的名称，歌手，购买的特定专辑的数量以及每张专辑的小计。我不明白如何从cart.items数组获取所需信息的逻辑。这是代码

    /** Program Description: This program simulates purchases using a 
 * loop. The program creates two classes; an album class, and
 * a cart class. The initial amount of money is $1000.00. The program
 * iterates through all the albums and purchases each one, as
 * long as there is money left. Every time an album gets purchased 
 * the initial amount of money is decremented by the purchase
 * price. Each time an item is purchased, it gets added to the cart.
 * The program then displays all the items purchased in the cart.
 * It should show the album name, artist name, quantity purchased,
 * and sub total for each. It then shows the total purchase price,
 * and the amount of money left over  
 * 
 *  Pseudocode:
 *  
 *      Create a constructor for Album object
 *      Create classes that inherit from Album
 *          Store these classes in an array
 *      Create a constructor for Cart object
 *      Create a const variable for initial money
 *      Loop to simulate purchases
 *          Iterate over an array of albums
 *          Purchase each one as long as there is money left
 *          Decrement money by purchase price
 *          Add item to cart
 *      Display info                                                    **/

// Create a constructor for Album class
function Album(title, artist, price){
    this.title = title;
    this.artist = artist;
    this.price = price;
    this.date = new Date();
    this.quantity = Math.floor((Math.random() * 10) + 1);
};
Album.prototype.purchase = function(){
    this.quantity--;
    if (this.quantity > 0){
        return 1;
    }
    else{
        return -1;
    }
};
// Create objects that inherit from Album
var pimpAButterfly = new Album("To Pimp a Butterfly", "Kendrick Lamar", 29.99);
pimpAButterfly.tracklisting = ["Wesleys Theory", "For Free", "King Kunta", "Institutionalized", "These Walls"];

var blameItAll = new Album("Blame It All On My Roots", "Garth Brooks", 29.98);
blameItAll.tracklisting = ["Blame It All On My Roots", "Neon Moon", "Papa", "Thunder Rolls"];

var killLights = new Album("Kill the Lights", "Luke Bryan", 20.83);
killLights.tracklisting = ["Kick the Dust Up", "Kill the Lights", "Strip it Down", "Home Alone Tonight"];

var platinum = new Album("Platinum", "Miranda Lambert", 20.61);
platinum.tracklisting = ["Girls", "Platinum", "Little Red Wagon", "Priscilla", "Automatic"];

var painKiller = new Album("PainKiller", "Little Big Town", 24.99);
painKiller.tracklisting = ["Quit Breaking Up With Me", "Day Drinking", "Tumble and Fall", "Painkiller"];

// Store these objects in an array
var albums = [pimpAButterfly, blameItAll, killLights, platinum, painKiller];
// Create a constructor for Cart class
function Cart(val){
    this.items = [];
};

Cart.prototype.add = function(val){
    this.items.push(val);
};

Cart.prototype.remove = function(val){
    this.items.splice(albums.indexOf(val), 1);
};

//Create a constant variable for initial money
var INITIAL_MONEY = 1000.00;

// Create an instance of the Cart object
var cart = new Cart();

// Calculate cheapest album price
var cheapestPrice = albums[0].price;
for (var j = 1; j < albums.length; j++)
    if (albums[j] < cheapestPrice){
        cheapestPrice = albums[j];
    };

// Loop to simulate purchases
var i = 0;
while(INITIAL_MONEY >= cheapestPrice){
    i = 0;
    while(i < albums.length){
        //Purchase each one as long as there is money left
        if (INITIAL_MONEY >= cheapestPrice){
            albums[i].purchase();
            //Decrement money by purchase price
            INITIAL_MONEY = INITIAL_MONEY - albums[i].price;
            //Add item to cart
            cart.add(albums[i]);
        }
        i++;
    }
};


console.log(cart.items);
/**console.log("Album Name\tArtist Name\tQuantity\tSubtotal");
for(var count = 0; count < cart.items.length; count++)**/

Answer 1

循环浏览购物车并总结所需的信息，这里有一些伪代码：

for(var count = 0; count < cart.items.length; count++){
  var item = cart.items[count];
  //item is now an album, now sum up the quantities into a results array, pseudocode:
  results[item] += item.quantity
}

//loop through your results and display all information:

for(var count = 0; count < results.length; count++){
 console.log("Album: "+results[count].title);
 console.log("Artist: "+results[count].artist);
 console.log("Quantity: "+results[count].quantity);
 console.log("Subtotal: "+results[count].price * results[count].quantity);
}

编辑：这将统计购物车中的相册：

var counts = {};
cart.items.forEach(function(x) { counts[x.title] = (counts[x.title] || 0)+1; });
console.log(counts);

如何使用具有相同元素的数组多次

1 个答案: