Javascript 中的內部聯接

Question

 const products = [{ id: 5, productName: "Logitech Mouse", unitprice: 35 }, { id: 6, productName: "Logitech Keyboard", unitprice: 40 } ]; const cart = [{ id: 101, userId: 3, productId: 5, quantity: 2 }, { id: 102, userId: 3, productId: 6, quantity: 1 } ];

使用對象中的這些數據，我如何將購物車的productId內部連接到 product 的id ？ 這樣輸出將是：

羅技鼠標, 35, 2 羅技鍵盤, 40, 1

Answer 1

我會要求您先嘗試自己，然后再尋求幫助，以便以最佳方式從社區獲得幫助。

您可以嘗試使用.map()和find()進行解構賦值：

 const products = [{ id: 5, productName: "Logitech Mouse", unitprice: 35 }, { id: 6, productName: "Logitech Keyboard", unitprice: 40 } ]; const cart = [{ id: 101, userId: 3, productId: 5, quantity: 2 }, { id: 102, userId: 3, productId: 6, quantity: 1 } ]; var res = products.map(({id,...rest}) => { var cartObj = cart.find(c => c.productId == id); rest.quantity = (cartObj != undefined && 'quantity' in cartObj) ? cartObj.quantity : 'N/A'; return rest; }); console.log(res);

Answer 2

您可以采用更像 SQL 的方法為產品創建哈希表，並使用哈希表中對象的所需屬性和quantity映射購物車

結果，您將獲得具有產品名稱、單價和數量的新對象。

 const select = (keys, object) => Object.fromEntries(keys.map(k => [k, object[k]])), products = [{ id: 5, productName: "Logitech Mouse", unitprice: 35 }, { id: 6, productName: "Logitech Keyboard", unitprice: 40 }], cart = [{ id: 101, userId: 3, productId: 5, quantity: 2 }, { id: 102, userId: 3, productId: 6, quantity: 1 }], productsMap = products.reduce((r, o) => (r[o.id] = o, r), {}), result = cart.map(({ productId, quantity }) => ({ ...select(['productName', 'unitprice'], productsMap[productId]), quantity })); console.log(result);

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