FarNet.JavaScriptFar 2.0.2

FarNet.JavaScriptFar

JavaScriptFar runs JavaScript scripts in .NET with FarNet API for Far Manager scripting.

• Installation
• Run commands
• Run scripts
• Parameters
• Global variables
• Folder sessions
• Debugging
• See also

The module is built with Microsoft ClearScript and Google V8 JavaScript engine.

Installation

• Far Manager
• Package FarNet
• Package FarNet.JavaScriptFar

How to install and update FarNet and modules
https://github.com/nightroman/FarNet#readme

Run commands

JavaScript statements and expressions are run from the command line with the prefix js:

js: pi = Math.PI
js: Math.sqrt(pi)

Run scripts

You can open scripts in the editor and run by pressing [F5]. The result value, if any, is shown in the title or a new editor.

Or you can run scripts from the command line using js:@ and a script path. Paths may be absolute or relative to the current panel folder. Environment variables are expanded.

js: @ hello-world.js
js: @ %scripts%\hello-world.js

Create the file association for *.js scripts and run current scripts from panels by [Enter]:

*.js;*.cjs;*.mjs
js:@!\!.!

The following extra prefixes may be specified before @:

• task: tells to start the script or command as a task

Example:

js: task: @ too-slow.js

Scripts running as tasks should not call Far API unless it is designed for multi-threaded scenarios and documented accordingly.

Parameters

In order to pass parameters to scripts, use :: after the file name followed by semicolon separated key=value pairs (connection string format):

js: @ user.js :: name = John Doe; age = 42

These parameters are available in JavaScript as the property bag variable args.

The special parameter _session may define the target folder session path.

Parameters apply to commands as well. This example calls test defined in a particular session (e.g. auto loaded by session scripts) and sends the file parameter:

js: test(args.file) :: _session=C:\Test; file=C:\Test\test1.json

Global variables

• args - property bag of named parameters from command line or interop
• host - extended JavaScript functions provided by ClearScript, see here
• far - FarNet main methods, shortcut to clr.FarNet.Far.Api see here
• clr - .NET types of the following assemblies:
  • mscorlib
  • System
  • System.Core
  • System.Diagnostics.Process
  • System.Numerics
  • System.Runtime
  • ClearScript.Core
  • FarNet

Folder sessions

JavaScript files and commands are run in "folder sessions". The script folder or the current panel folder is used if it contains a file like _session.*. Otherwise the main folder %FARPROFILE%\FarNet\JavaScriptFar is used. Its session files, if any, work for all scripts and commands with no own session.

Any file _session.* engages its folder session on running scripts and commands, even if the file is not used by the module, e.g. _session.txt.

Used session files:

• Configuration file _session.xml

  This file configures the session JavaScript engine. The existing file is edited or a new is created by F11 / JavaScriptFar / Configuration. This is the recommended way of editing configurations, it validates the schema and some data.

  For configuration values and doc comments, see SessionConfiguration.cs.

• Session scripts, *.js, *.cjs, *.mjs in _session.*

  All session scripts are loaded once, in alphabetical order, case ignored. Other scripts in this folder or others for the main session may use the assets defined by session scripts.

You may view created sessions by F11 / JavaScriptFar / Sessions. Keys and actions:

• [Enter] - go to the session folder.
• [Del] - close the session.

Normally you do not have to close sessions, they do not consume much resources unless you store a lot of data in session variables. But closing may be useful on development, on changes in sessions files, for terminating debugged session (marked with a tick), and etc.

Debugging

Prerequisites:

• Install VSCode (this should make code.cmd available in the path).
• Set up ClearScript V8 debug launch, see VII. Debugging with ClearScript and V8.

To start debugging of the current folder session, use F11 / JavaScriptFar / Start debugging. This terminates other debugged sessions, if any. Just one session may be debugged at a time.

VSCode is opened. Prepare the session for debugging in VSCode. Open scripts and set breakpoints. Optionally enable breaks on caught / uncaught exceptions.

Then start the ClearScript V8 debugger in VSCode, ensure it is selected as the current and press [F5].

Switch to Far Manager and run a script or command. The debugger breaks on hit breakpoints, some exceptions, and debugger statements in the JavaScript code.

VSCode debugger is useful for examining variable values, object properties and methods, typing commands in the debug console, watching the output of console functions.

See also

• Samples - demo scripts presenting features and techniques.
• FarNet.ScottPlot - interactive plots, JavaScript samples.
• JavaScript in Visual Studio Code