JavaScript 中的 BigDecimal
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BigDecimal in JavaScript
提问by SnakeDoc
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.
我对 JavaScript 非常陌生（我来自 Java 背景），我正在尝试用少量资金进行一些财务计算。
My original go at this was:
我最初的做法是：
<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) + '<br/>' +
'15% Off: $' + (Math.ceil(per15 * 100) / 100).toFixed(2) + '<br/>'
);
</script>
This worked well except it always rounded up (Math.ceil). Math.floorhas the same issue, and Math.roundis also no good for floats.
这很有效，只是它总是四舍五入 ( Math.ceil)。Math.floor有同样的问题，Math.round也不适合花车。
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.
在 Java 中，我会从一开始就完全避免使用浮点数，但是在 JavaScript 中似乎没有默认包含类似的东西。
The problem is, all the libraries mentioned are either broken or for a different purpose. The jsfromhell.com/classes/bignumberlibrary 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_UPsomehow winds up as 3.72 when it should be 3.71.
问题是，所有提到的库要么坏了，要么用于不同的目的。该jsfromhell.com/classes/bignumber库非常接近我需要的东西，但是我在它的舍入和精度方面遇到了奇怪的问题......无论我将 Round Type 设置为什么，它似乎都可以自行决定。因此，例如，精度为 2 且圆形类型ROUND_HALF_UP为 3.72 的3.7107 以某种方式结束，而本应为 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.
我也尝试过@JasonSmith BigDecimal 库（Java 的 BigDecimal 的一个机器端口），但它似乎是用于 node.js 的，我没有运行的选项。
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?
我如何使用 vanilla JavaScript（并且可靠）来实现这一点，或者是否有我可以使用的现代（上面提到的那些现在已经有好几年了）库被维护并且没有损坏？
采纳答案by John Strickler
I like using accounting.jsfor number, money and currency formatting.
我喜欢accounting.js用于数字、货币和货币格式。
Homepage- https://openexchangerates.github.io/accounting.js/
主页- https://openexchangerates.github.io/accounting.js/
回答by laffuste
There are several implementations of BigDecimal in js:
BigDecimal 在js中有几种实现：
The last 3 come from the same author: see the differences.
最后 3 个来自同一作者：查看差异。
