JavaScript中的BigDecimal [英] BigDecimal in JavaScript

问题描述

我原来是JavaScript的新手（我来自Java背景），我正在尝试用少量的资金进行一些财务计算。去这是：

 < script type =text / javascript> 
 var normBase =（[price]）。replace（$，）; 
 var salesBase =（[saleprice]）。replace（$，）; 
 var base; 
 if（salesBase！= 0）{
 base = salesBase; 
} else {
 base = normBase; 
} 
 var per5 =（base  - （base * 0.05））; 
 var per7 =（base  - （base * 0.07））; 
 var per10 =（base  - （base * 0.10））; 
 var per15 =（base  - （base * 0.15））; 
 document.write 
（
'5％Off：$'+（Math.ceil（per5 * 100）/ 100）.toFixed（2）+'< br />' + 
'7％Off：$'+（Math.ceil（per7 * 100）/ 100）.toFixed（2）+'< br />'+ 
 '10％Off：$ （Math.ceil（per10 * 100）/ 100）.toFixed（2）+'<>'+ 
 '15'Off：$'+（Math.ceil（per15 * 100） / 100）.toFixed（2）+'< br />'
）; 
< / script> 
  

除了总是四舍五入（ Math.ceil ）。 Math.floor 具有相同的问题，并且 Math.round 对浮点数也是没有好处的。

在Java中，我将避免从开始就完全使用浮点数，但是在JavaScript中似乎没有默认的可比较的东西（OMG WHY！？！？所以，我的SO-fu让我看到这个帖子： 是一个很好的JavaScript的bigdecimal库> https://stackoverflow.com/questions/744099/is-there-a-good-javascript-bigdecimal-library

问题是，所提及的所有库都被破坏或用于不同的目的。 jsfromhell.com/classes/bignumber 图书馆非常接近我所需要的，但是我有四舍五入的问题和精确度...无论我设置了什么圆型到，似乎是自行决定的。因此，例如，精度为2的3.7107和 ROUND_HALF_UP 的圆形类型应该是3.71，但应该是3.71。

我也试过了@JasonSmith BigDecimal库（从Java的BigDecimal中加工过的一个端口），但它似乎是node.js，我没有选择运行。

如何使用vanilla JavaScript（而且是可靠的）或者是否有现代的（上面提到的都是现在的岁数）库我可以用这个是保持和不被破坏？

解决方案

我喜欢使用 accounting.js 数字，货币和货币格式。

首页 - https://openexchangerates.github.io/accounting.js/

Github - https://github.com/openexchangerates/accounting.js

I'm very new to JavaScript (I come from a Java background) and I am trying to do some financial calculations with small amounts of money.

My original go at this was:

<script type="text/javascript">
    var normBase = ("[price]").replace("$", "");
    var salesBase = ("[saleprice]").replace("$", "");
    var base;
    if (salesBase != 0) {
        base = salesBase;
    } else {
        base = normBase;
    }
    var per5  = (base - (base * 0.05));
    var per7  = (base - (base * 0.07));
    var per10 = (base - (base * 0.10));
    var per15 = (base - (base * 0.15));
    document.write
        (
        '5% Off: $'  + (Math.ceil(per5  * 100) / 100).toFixed(2) + '<br/>' +
        '7% Off: $'  + (Math.ceil(per7  * 100) / 100).toFixed(2) + '<br/>' +
        '10% Off: $' + (Math.ceil(per10 * 100) / 100).toFixed(2) + '<br/>' +
        '15% Off: $' + (Math.ceil(per15 * 100) / 100).toFixed(2) + '<br/>'
    );
</script>

This worked well except it always rounded up (Math.ceil). Math.floor has the same issue, and Math.round is also no good for floats.

In Java, I would have avoided the use of floats completely from the get-go, however in JavaScript there does not seem to be a default inclusion of something comparable (OMG WHY!?!?!?!).

So, my SO-fu has led me to this post: https://stackoverflow.com/questions/744099/is-there-a-good-javascript-bigdecimal-library

The problem is, all the libraries mentioned are either broken or for a different purpose. The jsfromhell.com/classes/bignumber library is very close to what I need, however I'm having bizarre issues with its rounding and precision... No matter what I set the Round Type to, it seems to decide on its own. So for example, 3.7107 with precision of 2 and round type of ROUND_HALF_UP somehow winds up as 3.72 when it should be 3.71.

I also tried @JasonSmith BigDecimal library (a machined port from Java's BigDecimal), but it seems to be for node.js which I don't have the option of running.

How can I accomplish this using vanilla JavaScript (and be reliable) or is there a modern (ones mentioned above are all years old now) library that I can use that is maintained and is not broken?

解决方案

I like using accounting.js for number, money and currency formatting.

Homepage - https://openexchangerates.github.io/accounting.js/

Github - https://github.com/openexchangerates/accounting.js

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