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Discussion on: Future Javascript: Javascript Pipeline Operators

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Replies for: Basically its just for readability. In the example above: addOne(multiplyByTwo(divideBySix(number))) Enter fullscreen mode Exi...

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akashkava profile image
Akash Kava •

Parsing benefit is very small compared to feature overhead. Also for better debugging chaining functions should be avoided, instead minizers can chain functions to reduce code size. And what about multiple parameters? I see no difference in terms of parsing benefit and syntax in below both styles.

var result = a 
    |> b(%) 
    |> c;
Enter fullscreen mode Exit fullscreen mode 
var x = b(a);
      x = c(x);
var result = x;
Enter fullscreen mode Exit fullscreen mode

The later has better visibility and easy to debug. The reason I am asking as I have written JavaScript engine for .NET, and we are incorporating more features and I want to implement upcoming features as part of test drive.

I certainly want to know the real benefit, for example ?? has benefit over || as ?? will only check for null or undefined and || will first call valueOf for objects and check if string is empty or not, leading to slower execution. ?. is not only a shorter syntax but faster execution as it will generate smaller machine instructions to duplicate value on stack without causing any overhead of storing value in a variable and evaluating it.

GitHub logo yantrajs / yantra

JavaScript Engine for .NET Standard

YantraJS

Yantra (Machine in Sanskrit) is a Managed JavaScript Engine for .NET Standard written completely in C#.

NuGet

Name Package
YantraJS (With CSX Module Support) NuGet
YantraJS.Core (Compiler) NuGet
YantraJS.ExpressionCompiler (IL Compiler) NuGet
WebAtoms.YantraJS NuGet

Documentation

  1. Introduction
  2. Expression Compiler
  3. JavaScript Engine

Discussions

We recommend using Github Discussion on this repository for any question regarding this product.

Special Thanks

  1. We are thankful to authors of Jurassic (we have incorporated number parser, promise and some unit tests from Jurassic.) github.com/paulbartrum/jurassic
  2. We are thankful to authors of EsprimaDotNet, we initially built prototype over EsprimaDotNet, but we chose to build our parser/scanner from scratch to support token spans. github.com/sebastienros/esprima-do...
  3. We are thankful to author of ILPack (we have incorporated saving IL to Assembly from this library.) github.com/Lokad/ILPack
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bamartindev profile image
Brett Martin •

For the first two points, if you are writing JS in a functional style then chaining functions is used often to compose functionality. In those instances, having a single input function is more common.

As far as the second example, if you want to avoid mutations / shadowing, the reassigning variables is something to avoid.

Again, these are personal choices on how to write the JS code. I guess its just part of the challenges of having multiple paradigms in a language. Here is the full proposal though, it will hopefully give more insight into the rationale: github.com/tc39/proposal-pipeline-...

Its still in Stage 2 and there appears to be outstanding questions around it since August.