JSConstraintsDebug

Article
12/15/2021

JSConstraintsDebug (JSConstraintsDebug.exe) is a command-line tool that provides debugging support for JavaScript Constraints while developing a V4 printer driver.

Where can I download JSConstraintsDebug?
JSConstraintsDebug.exe is included in the Microsoft Windows Driver Kit (WDK). For information about getting the WDK, see Windows Driver Kit downloads.

The tool executes each of the following relevant entry point APIs on the JavaScript constraints of the targeted driver against the user provided print ticket:

PTGetPrintCapabilities

PTConvertDevModeToPrintTicket

TConvertPrintTicketToDevMode

PTMergeAndValidatePrintTicket

During execution the tool will prompt for an appropriate IDE debugger such as Visual Studio. Upon selection, the constraints source code will be opened and stopped at a JavaScript debugger statement.

To debug JS constraints files, follow these steps:

Open a Command Prompt window.
Run the JSConstraintsDebug.exe tool and specify, at minimum, the printer name and the path to a test print ticket.
Choose the debugging tool you wish to use.

Running JSConstraintsDebug in user mode

Elevated privileges are required to enable debugging of JS functions. To run in user mode, the following registry key must be set prior to executing JSConstraintsDebug.exe:

Key name	HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print
Value name	EnableJavaScriptDebugging
Type	DWORD
Value	1

JavaScript debugger statements

Breakpoints can be created in JavaScript source by using the debugger statement. This will pause operation in Visual Studio all allow for step-by-step debugging. These statements can be inserted in any of the JavaScript Constraint APIs.

For example:

function validatePrintTicket(PrintTicket, scriptContext)
{
    debugger; // debug tool will pause at this breakpoint
    ...
}