javascript - 使银行余额出现在 javascript 存款/取款功能中

Question

我有一个银行余额文本字段，我想根据存款/取款不断更新。这是我的代码:

<label>Bank Balance:</label>
<br />
<input type="text" id="bankBalance" value="1000" />
<br />
<br />
<button id="deposit">Deposit</button>
<button id="withdraw">Withdraw  </button>

var balance = document.getElementById('bankBalance').value;
balance = Number(balance);

var withdraw = document.getElementById('withdraw');

deposit.addEventListener('click', depositCash);

function depositCash () {
  var depositAmt = prompt('How much would you like to deposit?');
  depositAmt = Number(depositAmt);
  balance = depositAmt + balance;

  return balance;
}

没有收到错误。为什么这不起作用？我将balance和depositAmt变量都转换为数字并添加它们。

谢谢!

Answer 1

你不能这样做:

return balance;

您需要将值设置回文档元素，例如

document.getElementById('bankBalance').value = balance