Question

出于某种原因，我在使用循环工作时遇到困难。每当我尝试测试它时，它一直会崩溃我的浏览器，在一个案例中，我能够在控制台中看到循环的结果，我所看到的只是NaN打印了好几次。我的代码中有没有遗忘的东西？

<div id="output"></div>

<script>

var starting = prompt("What is your starting balance?");
var target = prompt("What is your target balance?");
var interest = prompt("What is your interest rate?");
var periods = 0;

var current = starting;
var greaterThan = false;

while (greaterThan === false) {
  if (current < target) {
    current = current + (current * interest);
    periods++;
  } else {
    greaterThan = true;
    alert("it took " + periods + " periods to make your starting balance greater than your target balance.");
    document.querySelector('#output').textContent = "to grow an initial investment of " + starting + " to " + target + " at a " + interest + " interest rate will require " + periods + " investment periods.";
  }
}

</script>

Answer 1

我能看到的一个问题是，你的所有输入值都是字符串，而不是数字，所以他们正在进行字符串比较而不是数字

var starting = +prompt("What is your starting balance?") ||0;
var target = +prompt("What is your target balance?")||0;
var interest = +prompt("What is your interest rate?")||1;

+前面的prompt()是unary plus运算符

Answer 2

您忘记将提示中的结果从字符串转换为数字。

var starting = parseFloat(prompt("What is your starting balance?"));

对用户从提示输入的其他数字执行相同的操作。

Answer 3

首先，您需要将输入转换为整数值。提示输入是一个字符串。即使你输入1或10或任何数字。你可以使用parseInt（）。而且因为你要求利率，我认为任何用户都会输入类似2.5或10的百分比。不是0.1或0.05。即使他这样做，parseInt（）函数也不能正确，因为0.05不是整数值。你可以使用parseFloat。所以我建议你看下面我的代码实现。另外，我省略了if else语句，因为它们不是必需的，只会使代码更复杂。

<div id="output"></div>

<script type="text/javascript">

var starting = parseInt(prompt("What is your starting balance?"));
var target = parseInt(prompt("What is your target balance?"));
var interest = parseInt(prompt("What is your interest rate?"));
var periods = 0;
var intrate = interest/100;
var current = starting;

while (current< target) {

    current += (current*intrate);
    periods += 1;
  } 
    alert("it took " + periods + " periods to make your starting balance greater than your target balance.");
    document.querySelector('#output').textContent = "to grow an initial investment of " + starting + " to " + target + " at a " + interest + " interest rate will require " + periods + " investment periods.";
</script>

为什么这个while循环导致无限循环？

3 个答案: