新構造的返回值 object 返回之前創建的值

Question

我在 javascript 中練習 OOP 有以下挑戰：

世行應允許我們：

添加客戶

• 客戶應該能夠存款。
• 客戶應該可以提取金額。
• 客戶應該能夠看到他/她的帳戶。

所以我做了以下，我用不同的方法創建了一個 Bank class。

它似乎與一個人一起工作正常，但我的問題是，一旦我添加了一個新客戶，並在新客戶上運行這些方法，它就會返回第一個客戶的價值。

 class Bank { constructor() { this.customers = []; } addCustomer(customer) { this.customers.push({ name: customer, account: 0 }); } printAccount(customer) { if (this.customers.some((person, idx) => person.name === customer)) { console.log( `${this.customers[0].name}'s account is ${this.customers[0].account}` ); } else { console.log("no access"); } } depositAmount(customer, amount) { if (this.customers.some(person => person.name === customer)) { this.customers[0].account += amount; } else { return; } } withdrawAmount(customer, amount) { if (this.customers.some(person => person.name === customer)) { this.customers[0].account -= amount; } else { return; } } } const bank = new Bank(); bank.addCustomer("daniel"); bank.depositAmount("daniel", 10); bank.withdrawAmount("daniel", 5); bank.printAccount("daniel"); bank.addCustomer("gwen"); bank.depositAmount("gwen", 10); bank.printAccount("gwen"); console.log(bank);

Answer 1

你總是在你的方法中使用this.customers[0] ，所以它總是對第一個客戶進行操作。

使用find()找到客戶 object，並使用它。

 class Bank { constructor() { this.customers = []; } addCustomer(customer) { this.customers.push({ name: customer, account: 0 }); } getCustomer(name) { return this.customers.find(person => person.name == name); } printAccount(name) { const customer = this.getCustomer(name); if (customer) { console.log( `${customer.name}'s account is ${customer.account}` ); } else { console.log("no access"); } } depositAmount(name, amount) { const customer = this.getCustomer(name); if (customer) { customer.account += amount; } } withdrawAmount(name, amount) { this.depositAmount(name, -amount); } } const bank = new Bank(); bank.addCustomer("daniel"); bank.depositAmount("daniel", 10); bank.withdrawAmount("daniel", 5); bank.printAccount("daniel"); bank.addCustomer("gwen"); bank.depositAmount("gwen", 10); bank.printAccount("gwen"); console.log(bank);

Answer 2

您應該改用find ：

  depositAmount(customer, amount) {
    const customer = this.customers.find((person) => person.name === customer);

    if (!customer) return; // no customer exists

    customer.account += amount; // add to customer
  }

如果沒有找到客戶，它會返回undefined ，您可以檢查一下。