Js Lazarus Pascal Reference Documentation
Js
Current Version: 11.6.0
Chilkat.Js
Use
Run JavaScript code from inside the host application without launching an
external scripting process.
Start from a restricted execution environment and selectively expose only
the capabilities the script should use.
Allow scripts to use selected Chilkat classes when the host application
wants JavaScript to perform controlled Chilkat operations.
Optionally restrict filesystem access so scripts can read or write only
within approved locations.
Execute JavaScript, pass data through the host-controlled environment,
and retrieve results or diagnostics from the script run.
Use JavaScript as an embedded extension language for application-defined
workflows while keeping host resources protected.
For an extended overview, see
Js Class Overview.
Also see
About the Chilkat.Js JavaScript Engine.
Execute sandboxed JavaScript inside an application with controlled access to Chilkat features.
Chilkat.Js when an application needs to execute JavaScript
internally while retaining control over what the script is allowed to access.
By default, scripts run in a closed sandbox with the JavaScript language and
standard library available, but without filesystem, network, or Chilkat
class access unless the host application explicitly enables those
capabilities.
Embedded JavaScript engine
Sandboxed by default
Enable Chilkat classes
Filesystem restrictions
Script input and output
Controlled automation
Js object, load or provide the JavaScript code, enable
only the Chilkat classes and filesystem locations the script is permitted to
use, run the script, and inspect the result or diagnostic output. Use
Chilkat.Js when the application needs scriptability with a
security boundary controlled by the host.
Create / Free
uses
Chilkat.Js;
var
obj: TJs;
begin
obj := TJs.Create;
try
if not obj.IsValid then
raise Exception.Create('Failed to create a TJs instance.');
// ... use obj ...
finally
obj.Free;
end;
end;
Allocates the underlying CkJs object and returns a new TJs instance. Simply adding Chilkat.Js to the unit's uses clause is enough to locate and bind to the Chilkat shared library (DLL / .so / .dylib) at runtime — no separate load step is required. Check obj.IsValid after calling Create; it is False if the underlying library could not be found/loaded or the object could not be allocated (for example, when unlicensed).
Every TJs created by calling Create should eventually be released by calling .Free (inherited from TObject). The destructor automatically disposes the underlying CkJs handle. A native (unmanaged) memory leak occurs if the object is never freed.
Properties
DebugLogFilePath
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.
LastErrorHtml
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.
topLastErrorText
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.
LastErrorXml
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.
topLastMethodSuccess
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.
TimeoutSeconds
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.
VerboseLogging
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.
Version
Methods
CallFunction
// resultJson is a TJsonObject object.
function CallFunction(funcJson: TChilkatBase;
resultJson: TChilkatBase): Boolean;
Calls a JavaScript function. The function name and arguments are passed in funcJson. The result is returned in resultJson.
Returns True for success, False for failure.
ConsoleOutputSb
procedure ConsoleOutputSb(sb: TChilkatBase);
Eval
// resultJson is a TJsonObject object.
function Eval(jscript: TChilkatBase;
resultJson: TChilkatBase): Boolean;
Run jscript as a script. Return output and errors in resultJson.
Returns True for success, False for failure.
SetCkPermission
const permission: string): Boolean;
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.