Debug Object (JavaScript)

An intrinsic global object that sends output to a debugger.




You do not instantiate the Debug object. You can access all its properties and methods by calling function.

There are different ways to debug Internet Explorer and Windows 8.x Store apps. In Windows 8.x Store apps, the write and writeln functions of the Debug object display strings in the Visual Studio Output window at run time. For more information about debugging Windows 8.x Store apps, see Debug Windows Universal Apps in Visual Studio.

To debug Internet Explorer scripts, you must have a script debugger installed and the script must run in debug mode. Internet Explorer 8 and later versions include the JavaScript debugger. If you are using an earlier version of Internet Explorer, see How to: Enable and Start Script Debugging from Internet Explorer.

If the script is not being debugged, the functions have no effect.


This example uses the write function to display the value of the variable.

var counter = 42;  
Debug.write("The value of counter is " + counter);  


Supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards, Internet Explorer 11 standards. Also supported in Store apps (Windows 8 and Windows Phone 8.1). See Version Information.


Debug Constants


Debug.debuggerEnabled Property | Debug.setNonUserCodeExceptions Property


Debug.msTraceAsyncCallbackStarting Function | Debug.msTraceAsyncCallbackCompleted Function | Debug.msTraceAsyncOperationCompleted Function | Debug.msTraceAsyncOperationStarting Function | Debug.msUpdateAsyncCallbackRelation Function | Debug.write Function | Debug.writeln Function

See Also

debugger Statement