decimal.js VS proposal-pattern-matching

ii) Third-Party Libraries There are various libraries like math.js, decimal.js, big.js that solve the problem. Each library functions according to its documentation. This approach is comparatively better.

Desperate for a solution, I stumbled upon Decimal.js, a JavaScript library that provides arbitrary-precision decimal arithmetic. I was intrigued, so I decided to give it a try.

I too wish JS had a dedicated Decimal Type, but there is plenty of 3rd party libraries available like decimal.js

For your particular example though, if we keep in mind that the input data to be validated is JSON-serializable, only a string could possibly accommodate the precision expected of a decimal from among the JSON-serializable JS primitives. You could use one or more regex patterns to describe the allowable permutations. The resultant schema would be cross-platform since it doesn't use custom keywords - nice! You can also use unions if you want to say that integers, NaN, and Infinity are also allowed per the docs there.

i've used Decimal.js to account for floating point issues in JS before. maybe this will help? I realize its not native and is a 3rd party lib - but its intent is to handle floating point issues and precision. That kinds sounds like the tree you're barking up right now. maybe it will help.

In the example provided, the name of the library is literally Decimal.js: https://mikemcl.github.io/decimal.js/

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?

Looks good! I love the idea of the embedded calculator

I noticed that it doesn't handle remainder/modulo (%) equations:

"10 % 2" results in: "Left hand side of addition cannot be a percentage."

It does look like decimal.js can handle that: https://mikemcl.github.io/decimal.js/#mod

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

https://github.com/MikeMcl/decimal.js/ great library

Note, however, that there is a proposal to add pattern matching to JS.

There's an ECMAScript proposal that is in the works to add this feature to the language! It's going to look something like this.

More importantly, TypeScript typically commits to build things into itself when the proposal in JavaScript reaches Stage 3. The pattern matching proposal in JavaScript is Stage 1, but depends on many other proposals as well that may or may not need to be at Stage 3 as well for it to work. This particular proposal is interested on pattern matching on JavaScript Objects and other primitives, just like Python does with it’s native primitives. These are also dynamic types which helps in some areas, but makes it harder than others. Additionally, the JavaScript type annotations proposal needs to possibly account for this. So it’s going to be awhile. Like many years.

For true™ functional programming in JS, native pattern matching and partial function application are missing (at least for now: 1, 2). For proper OOP, it lacks real interfaces and compile-time dependency injection.

The proposal for pattern matching syntax seems more akin to what they're looking for.

https://github.com/tc39/proposal-pattern-matching

There's a proposal to add something like that to JavaScript but it's been stuck in limbo since 2017 although there are libraries like ts-pattern which implement it already.

I'll admit, it is easy to assert that the TypeScript language should not be involved in the matters of packages but I also wonder if we're moving towards a point where interfaces will be as common as namespaces and whether or not it would be sensible for the language to incorporate such type assertions into the language formally, after all, it already compiles to various forms of JavaScript and there is a stage 1 proposal submitted to the TC39 committee to give JavaScript pattern matching. If adopted, wouldn't it make sense to allow TypeScript to compile a type into a type guard for the native JavaScript pattern matcher?

Both are active tc39 proposals :)

https://github.com/tc39/proposal-pipeline-operator - Stage 2

https://github.com/tc39/proposal-pattern-matching - Stage 1

Hopefully we get both in the next couple of years.

We often add promising TC39 proposals into Civet so people can experiment without waiting.

We've added https://github.com/tc39/proposal-pipeline-operator, a variant of https://github.com/tc39/proposal-pattern-matching, a variant of https://github.com/tc39/proposal-string-dedent and others.

Since our goal is to be 99% compatible with ES we'll need to accommodate any proposals that become standard and pick up anything TC39 leaves on the table (rest parameters in any position, etc.)