将正数转换为负数

问题描述

我想使用减号将数​​字显示为负数：5000->-5000

<div class="cart-summary-line" id="cart-subtotal-discount">
  <span class="label">
    Remise
  </span>
  <span class="value">5,000&nbsp;TND</span>
</div>

这是我关于自定义JS的文章，但数字仍然显示为正。

$(document).ready(function() {
  return "-" + ($(['#cart-subtotal-discount'.value]).html(5.000));
});

解决方法

您的JavaScript和jQuery语法有很多问题。我建议您重新阅读jQuery documentation and examples。

$(document).ready(function() {
  return "-"+($(['#cart-subtotal-discount'.value]).html(5.000));
// ^ we don't need the return value
//        ^ concatenating a "-" here won't set anything
//           ^ don't need the extra parentheses here
//              ^ why square brackets? this isn't an array
//                ^ this selector contains a lot more text than just the number
//                                        ^ do we want `value` or `html`?
//                                        ^ are we getting,setting,or both?
//                                                      ^ `5.000` means `5` in JS,not `5000`

});

这是您可能实现的目标的一种方法：

const positiveNumber = 5000
const negativeNumber = 0 - positiveNumber
const locale = 'ar-TN' // Tunisian locale,assumed from "TND" currency

// Using `toLocaleString` with the ar-TN locale will give you
// the "5.000" formatting you want,but you still need to
// write the number as `5000` in JavaScript.
const formattedNumber = negativeNumber.toLocaleString(locale)

$(document).ready(function() {
  $('#amount').html(formattedNumber)
})

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<p>Remise <span id="amount"></span>&nbsp;TND</p>