新构造的返回值 object 返回之前创建的值

Question

I have the following challenge for practicing OOP in javascript:

The Bank should allow us to:

Add customers

• A customer should be able to deposit an amount.
• A customer should bevable to withdraw an amount.
• A customer should be able see his/her account.

So I did the following, I created a Bank class with different methods.

It seems to work fine with 1 person, but my problem is once I add a new customer, and run the methods on the new customer it returns the value of the first customer.

 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

You're always using this.customers[0] in your methods, so it always operates on the first customer.

Use find() to find the customer object, and use that.

 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

You should use find instead:

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

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

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

If there was no customer found, it returns undefined and you can check for that.