bigint的JSON传输：12000000000002539转换为12000000000002540？ [英] JSON transfer of bigint: 12000000000002539 is converted to 12000000000002540?

问题描述

我正在传输原始数据，例如 [{id：12000000000002539，名称：Some Name}] ，我得到的对象 [{id：12000000000002540，名称：Some Name}] 解析后，现在服务器端将id转换为字符串似乎有所帮助。
但是有没有更好的方法来正确传输bigint数据？

I'm transferring raw data like [{id: 12000000000002539, Name: "Some Name"}] and I'm getting the object [{id: 12000000000002540, Name: "Some Name"}] after parsing, for now server side converting id into string seems to help. But is there a better way to transfer bigint data correctly?

推荐答案

该值实际上是不是超过JavaScript中的最大数值（仅1.7 ³⁰⁸ 左右）。

The value is actually not exceeding the maximum numeric value in JavaScript (which is "only" 1.7³⁰⁸ or so).

但是，值 超出积分精度的范围。并不是发送了错误的数字：而是 literal 12000000000002539 只能表示为 12000000000002540，因此从不 JavaScript中的正确数值。 （积分范围约为+/- 2 ⁵³ 。）

However, the value is exceeding the range of "integral precision". It is not that the wrong number is sent: rather, it is that the literal 12000000000002539 can only be represented as precisely as 12000000000002540, and thus there was never the correct numeric value in JavaScript. (The range of integrals is about +/- 2⁵³.)

这是一个使用 双相对精度 （IEEE-754中的binary64）类型，用于存储所有数值，包括整数：

This is an interesting phenomena of using a double relative-precision (binary64 in IEEE-754 speak) type to store all numeric values, including integers:

12000000000002539 === 12000000000002540 // true

最大有效数字精确存储为数值的十进制数字是15（真的是15.95）。在上面，有17个有效数字，因此一些最不重要的信息会无声地丢失。在这种情况下， as JavaScript解析器/引擎读入文字值。

The maximum significant number of decimal digits that be precisely stored as a numeric value is 15 (15.95, really). In the above, there are 17 significant digits, so some of the least-significant information is silently lost. In this case, as the JavaScript parser/engine reads in the literal value.

唯一可以安全处理这种大小的整数的方法JavaScript是使用字符串文字或以另一种方式将其分解（例如自定义数字类型或bigint图书馆）。但是，我建议只使用字符串，因为它是人类可读的，相对紧凑的（JSON中只有两个额外的字符），并且不需要特殊的序列化。由于在这种情况下该值只是一个id，我希望数学不需要在它上面执行：）

The only safe way to handle integral numbers of this magnitude in JavaScript is to use a string literal or to break it down in another fashion (e.g. a custom numeric type or a "bigint library"). However, I recommend just using a string, as it is human readable, relatively compact (only two extra characters in JSON), and doesn't require special serialization. Since the value is just an "id" in this case, I hope that math does not need to be performed upon it :)

快乐编码。

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