FrontSubmit

Wolfram Kernel

Execution environment

Notebook`Editor`Kernel`FrontSubmitService`

Context

wljs-editor

Package

Sends an expression to be executed on WLJS Interpreter (frontend / browser)

FrontSubmit[expr_, opts___]

Options

"Window"

specifies a window socket, to which an expression will be sent. Use CurrentWindow to fetch a window object from the evaluation context.

"Tracking"

by the default it is False. See below which benefits it gives to a user

Tracking

If it is enabled, FrontSubmit returns a reference to a group of instances created by this submission on the frontend. It is group into an object FrontEndInstanceGroup.

instanceGroup = FrontSubmit[expr_, opts__, "Tracking"->True];

Why do you need this?

Destroy

It is possible to destroy all instances created in the group by simply calling Delete

Delete[instanceGroup]

It can remove graphics primitives (Disk[], Line[] ...) you added to an existing graph, or anything else, which is identifiable as an instance.

Usage with Meta-Markers

Using an extension MetaMarker, one can execute an expression in the context of a specified container

FrontSubmit[expr_, m_MetaMarker, opts___]

warning

Be aware of a context loss in a case of an handler function called from outside the cell. Therefore "Window" option comes to provide the missing information about a window.

With[{win = CurrentWindow[]},
	(* normal evaluation context *)
	
	EventHandler[InputButton[], Function[Null,
		(* NO evaluation context *)
		
		FrontSubmit[Alert["Hello World"], "Window" -> win]
										(* provided explicitly *)
	]]
]

or another example with a timer SetTimeout

With[{win = CurrentWindow[]},
	(* normal evaluation context *)
	
	SetTimeout[
		(* NO evaluation context *)
		FrontSubmit[Alert["Boom"], "Window"->win]
	, 3000];
	
	"Hi there!"
]

tip

Please have a look at this guide - Advanced animation

Examples

Calling an WLJS (or Frontend) function

FrontSubmit[Alert["Hello World!"]]

which will produce a pop-up modal window.

Or to call a custom-defined Javascript function

cell 1

core.ShowReversed = async (args, env) => {
	const text = await interpretate(args[0], env);
	alert(text..split("").reverse().join(""));
}

cell 2

FrontSubmit[ShowReversed["Must be reversed..."]];

Controlling ViewBox

A typical graphics figure is usually a ViewBox. Here we mark its instance with a unique ID using MetaMarker

Plot[x, {x,0,1}, Epilog->{MetaMarker["pp"]}]

and then we can destroy it and replace with some other text

FrontSubmit[ViewBox`OuterExpression["Hello World"], MetaMarker["pp"]] 

Append objects to a static graph

We can append anything to a graphics canvas without reevaluation of a cell

cell 1

Plot[x, {x,0,1}, Epilog->{MetaMarker["pp"]}]

and then

cell 2

FrontSubmit[Arrow[RandomReal[{0,1}, {2,2}]], MetaMarker["pp"]]

to append an arrow to a marked graph