bignumber.js VS token-lists

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

Uniswap tokenlist format

We’re thrilled to announce that the Crypto.com DeFi Wallet has integrated Token Lists!

I know that in order to get the addresses of every ERC20 token, https://etherscan.io/ and https://tokenlists.org/ are the way to go.

It's important to note that Uniswap is decentralized and anyone can "list" anything for trading without asking anyone or going through any process. This means there are thousands of tokens, probably millions in the future, available to trade.

Users do not see these tokens unless they actively search them out. Uniswap uses the TokenList standard (https://tokenlists.org/) and by default users only see tokens such as the top 100 projects on CoinGecko. There are many lists created by reputable players such as Aave and Gemini which cover the entire gamut of projects users want to trade without exposing end users to scam tokens.

I believe this is a good system and has worked well as having any kind of listing process or even a DAO introduces subjectivity and provides points of capture for bad actors. With an open listing process and standards like TokenLists we can say that Uniswap is truly a public good and will be around as long as we need it which provides a guaranteed way to swap any asset for any other asset no matter who created it or how controversial it is which is a good primitive for humanity to be able to rely on.

This should get you there.