bignumber.js VS proposal-decimal

If you use floating-points for currency (instead of whole-numbers like you probably should) libraries like bignumber.js help keep your code away from the binary floating-point pitfalls of IEEE-754 which manifests in the standard JavaScript number type:

This issue (well, another one in a widely used JS library) is what brought me to dig deeper into these "arbitrary precision" libraries and understand why this happens. I thought they were using rational numbers, but that's not the case. And this is what led me to think about how to solve this problem.

ERC20 has decimals fields and must be handled with digit awareness. I wanted to use only one library, but I used both ether.js's BigNumber and bignumber.js (for display purpose).

Most programming languages ( JavaScript, PHP, Go, Python, Java, C# ) have built-in support or 3rd-party libraries for handling this data type, even though the internal implementations can differ:

I'm working on a project where users will enter numbers like 9,999,999,999.99999 (up to 15 digits, up to 5 of them decimal) and we are having a problem with Numbers losing precision beyond certain number of digits (a typical issue for IEEE Standard 754 Floating Point Numbers, the 0.1 + 0.2 problem). I've solved this problem in a few projects before with the help of decimal.js or bignumber,js . In those cases, we kept user-input as strings and used a few custom-made numeric textbox widgets to accommodate this. Unfortunately, those widgets were proprietary... Now I need one again, but can't find anything. Do they exist?

Either avoid floating-point, perhaps using BigInt, or use a library like BigNumber.js. (Incidentally, I wrote an eslint plugin to enforce its use.)

To solve the problem while JavaScript waits on its own BigDecimal API, you can use something like bignumber.js to perform your calculations.

You need to use something like BigNumber.js

Bloomberg are currently sponsoring Igalia to work on adding native Decimal number support to JavaScript.

https://github.com/tc39/proposal-decimal

This is an active proposal and was last discussed in the September 2023 meeting.

would it be possible, for example, to access the standard decimal library of C# or Python via Javascript, thus not having to wait for the TC39 spec / implementation? [1]

[1] https://github.com/tc39/proposal-decimal

There's a BigDecimal TC39 proposal to bring this kind of thing to the native language, but until then you have to choose between accuracy and performance.

To solve the problem while JavaScript waits on its own BigDecimal API, you can use something like bignumber.js to perform your calculations.

TC39 is now advancing Built-in decimal datatype in JavaScript.

given the popularity of javascript, it's about time we had better native tools for dealing with numbers in general, but it seems like the discussion is very slow on this front. for instance, the decimal proposal is still at stage 1 [1]. and no, BigInt does not solve that.

[1] https://github.com/tc39/proposal-decimal

In the future, JavaScript will hopefully get base 10 arithmetic: https://github.com/tc39/proposal-decimal