How can I invoke the the Gaussian Filter without specifying radius

I use the code below invoke the filter and i do not want to specify radius.
I want the form to open with the existing values.
When I remove the radius or _value. i get an error or nothing happens.
How can I not specify the radius and if this is mandatory, how can i get the current value?

   const result = await batchPlay(
               _obj: "gaussianBlur",
               radius: {
                  _unit: "pixelsUnit",
                  _value: 5 
               _options: {
                  dialogOptions: "display"