Js C# Reference Documentation

Js

Current Version: 11.4.0

Chilkat.Js is a small, embeddable JavaScript engine. It executes JavaScript code inside an application without requiring a browser or large runtime like Node.js. The Chilkat Js engine began as QuickJS, but after extensive redesign, refactoring, and hardening, it has evolved into a separate JavaScript engine maintained as part of the Chilkat platform.

See About the Chilkat.Js JavaScript Engine for more information.

This software includes portions of the QuickJS JavaScript engine
Copyright (c) 2017-2024 Fabrice Bellard
Licensed under the MIT License.

The Chilkat Js engine was originally derived from QuickJS but has been extensively modified

Object Creation

Chilkat.Js obj = new Chilkat.Js();

Properties

DebugLogFilePath
public string DebugLogFilePath {get; set; }

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

  • A timeout property set to 0, indicating an infinite timeout.
  • A hang occurring within an event callback in the application code.
  • An internal bug in the Chilkat code causing the hang.

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LastErrorHtml
public string LastErrorHtml {get; }

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorText
public string LastErrorText {get; }

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorXml
public string LastErrorXml {get; }

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastMethodSuccess
public bool LastMethodSuccess {get; set; }

Indicates the success or failure of the most recent method call: true means success, false means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.

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TimeoutSeconds
public int TimeoutSeconds {get; set; }
Introduced in version 11.4.0

Specify a timeout in seconds to prevent JavaScript from running indefinitely, such as in an infinite loop. By default, the value is 0, meaning no timeout is set and infinite loops will continue forever.

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VerboseLogging
public bool VerboseLogging {get; set; }

If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
public string Version {get; }

Version of the component/library, such as "10.1.0"

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Methods

CallFunction
public bool CallFunction(JsonObject func, JsonObject result);
Introduced in version 11.4.0

Calls a JavaScript function. The function name and arguments are passed in func. The result is returned in result.

Returns true for success, false for failure.

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CallFunctionAsync (C#) (PowerShell)
public Task CallFunctionAsync(JsonObject func, JsonObject result);
Introduced in version 11.4.0

Creates an asynchronous task to call the CallFunction method with the arguments provided.

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns null on failure

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ConsoleOutputSb
public void ConsoleOutputSb(StringBuilder sb);
Introduced in version 11.4.0

Returns the console output in sb from the last call to Eval .

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Eval
public bool Eval(StringBuilder jscript, JsonObject result);
Introduced in version 11.4.0

Run jscript as a script. Return output and errors in result.

Returns true for success, false for failure.

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EvalAsync (C#) (PowerShell)
public Task EvalAsync(StringBuilder jscript, JsonObject result);
Introduced in version 11.4.0

Creates an asynchronous task to call the Eval method with the arguments provided.

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns null on failure

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SetCkPermission
public bool SetCkPermission(string chilkatClassName, string permission);
Introduced in version 11.4.0

Sets sandbox related permissions for Chilkat objects. The chilkatClassName is the name of the Chilkat class (case-insensitive), such as Http, Rest, "MailMan", "Ftp2", "Ssh", etc. The chilkatClassName can also be set to "all" to apply the permission to all Chilkat classes.

Possible values for permission are:

  • disable - Your JavaScript code is not allowed to create an instance of the Chilkat class. A JavaScript exception is thrown when trying to create a Chilkat object of a class that is disabled.
  • sandbox - Objects for the Chilkat class can be instantiated in JavaScript, but they have no read or write access to the local filesystem.
  • readOnly - Objects for the Chilkat class can be instantiated in JavaScript and have read-only access to the local filesystem.
  • writeOnly - Objects for the Chilkat class can be instantiated in JavaScript and have write-only access to the local filesystem.
  • readWrite - Objects for the Chilkat class can be instantiated in JavaScript and have read/write access to the local filesystem.

By default, all Chilkat classes are disabled. Your application must enable "all" or specific Chilkat classes before calling Eval or CallFunction .

Returns true for success, false for failure.

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Events

AbortCheck
public event AbortCheckEventHandler OnAbortCheck;

Enables a method call to be aborted by triggering the AbortCheck event at intervals defined by the HeartbeatMs property. If HeartbeatMs is set to its default value of 0, no events will occur. For instance, set HeartbeatMs to 200 to trigger 5 AbortCheck events per second.

More Information and Examples

Chilkat .NET Framework Event Implementation

Args are passed using Chilkat.AbortCheckEventArgs

Event callback implementation:

private void js_OnAbortCheck(object sender, Chilkat.AbortCheckEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Js js = new Chilkat.Js();
js.OnAbortCheck += js_OnAbortCheck;

Chilkat .NET Core Event Implementation

Event callback implementation:

public void handleAbortCheck(out bool abort)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Js js = new Chilkat.Js();
// ...
Chilkat.Js.AbortCheck abortCheck = new Chilkat.Js.AbortCheck(handleAbortCheck);
js.setAbortCheckCb(abortCheck);
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PercentDone
public event PercentDoneEventHandler OnPercentDone;

This provides the percentage completion for any method involving network communications or time-consuming processing, assuming the progress can be measured as a percentage. This event is triggered only when it's possible and logical to express the operation's progress as a percentage. The pctDone argument will range from 1 to 100. For methods that finish quickly, the number of PercentDone callbacks may vary, but the final callback will have pctDone equal to 100. For longer operations, callbacks will not exceed one per percentage point (e.g., 1, 2, 3, ..., 98, 99, 100).

The PercentDone callback also acts as an AbortCheck event. For fast methods where PercentDone fires, an AbortCheck event may not trigger since the PercentDone callback already provides an opportunity to abort. For longer operations, where time between PercentDone callbacks is extended, AbortCheck callbacks enable more responsive operation termination.

To abort the operation, set the abort output argument to true. This will cause the method to terminate and return a failure status or corresponding failure value.

More Information and Examples

Chilkat .NET Framework Event Implementation

Args are passed using Chilkat.PercentDoneEventArgs

Event callback implementation:

private void js_OnPercentDone(object sender, Chilkat.PercentDoneEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Js js = new Chilkat.Js();
js.OnPercentDone += js_OnPercentDone;

Chilkat .NET Core Event Implementation

Event callback implementation:

public void handlePercentDone(int pctDone, out bool abort)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Js js = new Chilkat.Js();
// ...
Chilkat.Js.PercentDone percentDone = new Chilkat.Js.PercentDone(handlePercentDone);
js.setPercentDoneCb(percentDone);
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ProgressInfo
public event ProgressInfoEventHandler OnProgressInfo;

This event callback provides tag name/value pairs that detail what occurs during a method call. To discover existing tag names, create code to handle the event, emit the pairs, and review them. Most tag names are self-explanatory.

More Information and Examples

Chilkat .NET Framework Event Implementation

Args are passed using Chilkat.ProgressInfoEventArgs

Event callback implementation:

private void js_OnProgressInfo(object sender, Chilkat.ProgressInfoEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Js js = new Chilkat.Js();
js.OnProgressInfo += js_OnProgressInfo;

Chilkat .NET Core Event Implementation

Event callback implementation:

public void handleProgressInfo(string name, string value)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Js js = new Chilkat.Js();
// ...
Chilkat.Js.ProgressInfo progressInfo = new Chilkat.Js.ProgressInfo(handleProgressInfo);
js.setProgressInfoCb(progressInfo);
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TaskCompleted
public event TaskCompletedEventHandler OnTaskCompleted;

Called from the background thread when an asynchronous task completes.

Chilkat .NET Framework Event Implementation

Args are passed using Chilkat.TaskCompletedEventArgs

Event callback implementation:

private void js_OnTaskCompleted(object sender, Chilkat.TaskCompletedEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Js js = new Chilkat.Js();
js.OnTaskCompleted += js_OnTaskCompleted;

Chilkat .NET Core Event Implementation

Event callback implementation:

public void handleTaskIdCompleted(int taskId)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Js js = new Chilkat.Js();
// ...
Chilkat.Js.TaskIdCompleted taskIdCompleted = new Chilkat.Js.TaskIdCompleted(handleTaskIdCompleted);
js.setTaskIdCompletedCb(taskIdCompleted);
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