WLJS Notebook

x86/64

docker run -it \
  -v ~/wljs:"/home/wljs/WLJS Notebooks" \
  -v ~/wljs/Licensing:/home/wljs/.WolframEngine/Licensing \
  -v ~/wljs/tmp:/tmp \
  -p 8000:3000 \
  --name wljs \
  ghcr.io/wljsteam/wljs-notebook:3.1.3

brew install --cask wljs-notebook

Print ordering

We fixed a very old issue related to how printed messages are handled. Try it out:

Print["1"];
2
Print["3"];
4

By default, the dark theme is derived using a global window filter that inverts colors and adjusts hue and contrast. This is great for text and vector graphics, but it may confuse users when applied to raster images. We added a new option to address this:

See it in the UI section of the settings menu.

Improved slides export

We switched to less distracting offscreen rendering, and it now reports progress while rendering slides.

Typesetting

We added missing URL and File output representations.

URL["https://google.com?q=1"]

URL[(*VB[*)("https://google.com?q=1")(*,*)(*"1:eJxTTMoPSmNkYGAoZgESHvk5KWlMIB4vkAjLTC13SU3OL0osyS8KZgaKhAb5BIsB6YySkoJiK3399Pz89JxUveT8XPtCW0MAlAgTVQ=="*)(*]VB*)]

File["3.1.3.wln"]

File[(*VB[*)("3.1.3.wln")(*,*)(*"1:eJw1TksKwjAQjeIHBTd6AT1AC9IrFHXhqkH3qZnQ6DQDmdRe30nBzZs37zPMqaXGzZRSvBC4EVo3z9tO4OlhrOFF0SSKOvsXj+C2//Tdc9IylV4KPBgi65Wwj48ecaJXn7qh1QehI6GLpi/eXLhIIUGwei16T3ZAYL3PGRTXQk9cmPjq/Bem03VWdH6pAQTDcAyUpLIRpSrPZVWOGH4sqTPM"*)(*]VB*)]

If the file does not exist, the output will be shortened:

File["3.1.9.wln"]

File["3.1.9.wln"]

We also fixed the representation of the GeneralizedPower symbol.

GeneralizedPower[f, a, 2]

(*TB[*)GeneralizedPower[(*|*)(*VB[*)(f)(*,*)(*"1:eJxTTMoPSmNkYGAoZgESHvk5KWlMIB4vkAjLTC13SU3OL0osyS8KBinyAZNpACpjCyo="*)(*]VB*)(*|*), (*|*)a(*|*), (*|*)2(*|*)](*|*)(*1:eJxTTMoPSmNkYGAo5gUSYZmp5S6pyflFiSX5RcFMQBH3AACM5QhW*)(*]TB*)

Improved Animate/Manipulate

We added support for GraphicsComplex in the context of 2D graphics for our optimizer/transpiler (JIT), used in Manipulate, Animate, and Refresh expressions. This allows us to take advantage of efficient 2D rendering, as in this example:

(* Create and Discretize Region *)
disks = RegionUnion[Disk[{-1, 0}, 0.5], Disk[{1, 0}, 0.5], 
   Disk[{0, -1}, 0.5], Disk[{0, 1}, 0.5], Disk[{0, 0}, 0.25]];
region = RegionDifference[Disk[], disks];
R2 = RegionBoundary@DiscretizeRegion[region, AccuracyGoal -> 5];
(* Set up Region Operators *)
rdf = RegionDistance[R2];
rnf = RegionNearest[R2];
(* Time Increment *)
dt = 3 0.001;
(* Collision Margin *)
margin = 1.02 dt;
(* Starting Point for Emission *)
sp = 0.85 Normalize[{1, 1}];
(* Conditional Particle Advancer *)
advance[r_, x_, v_, c_] := 
 Block[{xnew = x + dt v}, {rdf[xnew], xnew, v, c}] /; r > margin
advance[r_, x_, v_, c_] := 
 Block[{xnew = x , vnew = v, normal = Normalize[x - rnf[x]]},
   vnew = Normalize[v - 2 v.normal normal];
   xnew += dt vnew;
   {rdf[xnew], xnew, vnew, c + 1}] /; r <= margin
   
(* Setup simulation *)
nparticles = 500;
ntimesteps = 600;

Module[{s, rplot = RegionPlot[R2], lasti = Infinity},
  Animate[
    If[lasti > i, 
      lasti = 1; (* reset inner state *)
      s = Table[{rdf[sp], sp, AngleVector[2 Pi RandomReal[]], 0}, nparticles]
    ];
    
    Do[s = (advance @@ # &) /@ s, {i-lasti}];
    lasti = i;
    
    Show[rplot, Graphics[{PointSize[.01],
      GraphicsComplex[s[[All, 2]], Point[Range[nparticles]],
        VertexColors -> (ColorData["Rainbow", (# - 1)/10] & /@ s[[All, 4]])]}]],
    {i, 1, ntimesteps, 1}, RefreshRate -> 60]
]

(*VB[*)(FrontEndRef["5bdffa11-0d4e-4b8d-97ae-e82581e9e94b"])(*,*)(*"1:eJxTTMoPSmNkYGAoZgESHvk5KRCeEJBwK8rPK3HNS3GtSE0uLUlMykkNVgEKmyalpKUlGhrqGqSYpOqaJFmk6FqaJ6bqploYmVoYplqmWpokAQCUzhZB"*)(*]VB*)

In this example, it simulates "photons" bouncing off the inner walls of a 2D region. Depending on the simulation speed, it may produce fewer frames per second, even though the target is set to 60.

Even more: we guarded the Animate widget against spamming the kernel with evaluation requests. The animation will not go faster than the communication link, rendering pipeline, and computation allow.

AnimatedImage, or how to export an animation

Applying AnimatedImage to Animate, AnimatePlot, or AnimateParametricPlot will automatically render all frames offscreen and return an AnimatedImage object containing all uncompressed frames.

animation = Animate[
  ParametricPlot[ReIm[(*SpB[*)Power[I(*|*),(*|*)-t](*]SpB*) + 3 (*SpB[*)Power[I(*|*),(*|*)t/3](*]SpB*)], {t,0,u}, 
    Epilog->{
      Arrow[{{0,0}, ReIm[(*SpB[*)Power[I(*|*),(*|*)-u](*]SpB*)]}], 
      Arrow[{ ReIm[(*SpB[*)Power[I(*|*),(*|*)-u](*]SpB*)], ReIm[(*SpB[*)Power[I(*|*),(*|*)-u](*]SpB*) + 3 (*SpB[*)Power[I(*|*),(*|*)u/3](*]SpB*)]}]
    }, PlotRange->{{-4,4}, {-4,4}}, GridLines->Automatic,
    PlotStyle->(*VB[*)(RGBColor[1, 0, 0])(*,*)(*"1:eJxTTMoPSmNiYGAo5gUSYZmp5S6pyflFiSX5RcEsQBHn4PCQNGaQPAeQCHJ3cs7PyS8qYgCDD/ZQBgMDnAEA4iUPRg=="*)(*]VB*)
  ]
, {u, 0.001, 4Pi}, RefreshRate->30, Appearance->None];

ai = AnimatedImage[animation, FrameRate->30];
ai

%28%2AVB%5B%2A%29%28CoffeeLiqueur%60Extensions%60Video%60Internal%60imgSymbol%24362558%29%28%2A%2C%2A%29%28%2A%221%3AeJxTTMoPSmNkYGAoZgESHvk5KRCeEJBwK8rPK3HNS3GtSE0uLUlMykkNVgEKW5gbJ6caW5jpJqeYJuuamBmn6CYaJBnrWliYpqQYmBkbmSWaAwCEHhV6%22%2A%29%28%2A%5DVB%2A%29

To export it, simply use the native Export function.

Export["ai.gif", ai]

If you prefer to do this asynchronously, set Asynchronous -> True; AnimatedImage will return a Promise:

Then[AnimatedImage[animation, Asynchronous->True], Function[result,
  ai = result;
  Beep[];
]];

This feature is available only in the WLJS Notebook desktop application because it relies on our custom rendering engine.

Experimental Symja backend support

Kudos to Axel Kramer, who managed to bring his creation, Symja, to the level of Wolfram Language!

Symja is an open-source, pure-Java computer algebra system (CAS) and symbolic math library designed to mimic the programming paradigm and syntax of Wolfram Mathematica.

It can run a WLJS Notebook in browser mode by executing Scripts/start.wls from our repository, similar to how it works with the Docker image. Note that it is still far from being a perfect replacement for Wolfram Engine / WolframScript, and many WLJS features are very buggy; some symbols are not yet implemented. However, this is a great starting point for branching off from Wolfram technologies completely.

Experiments with Woxi

Symja is not the only project trying to harness the power of WL. A relatively new project, Woxi, maintained by Adrian Sieber, is now actively developed.

Woxi — Wolfram Language interpreter implemented in Rust

Fast iterations on issues assisted by AI bring more and more features of WL. We are also currently trying to launch WLJS using Woxi as a backend for both kernels. Let's see how it goes! 2026 is fantastic.

MCP Server patches

Improved documentation search
New skills for all cell types
Smaller system prompt
Improved message reporting and tool calling
Improved message truncation

Release Notes 3.1.3