How to make presence visible or invisible of a textfield

I have a list of textfield, i use itextsharp (C#) to valorize them.
For example i valorize the textfield: "topmostSubform.Page1.codice_articolo_0" with:

form.SetField("topmostSubform.Page1.codice_articolo_0", "value ");
form.RegenerateField("topmostSubform.Page1.codice_articolo_0");

if i valorize the textfield, i must make it visible, else if it has no value, i must make it invisible.

For every textfield i add this script:

topmostSubform.Page1.codice_articolo_0::docReady - (JavaScript, client)

if (this.rawValue==null){

          if (this.presence=="visible")

                    this.presence="invisible";

}

else {

          if (this.presence=="invisible")

                    this.presence="visible";

}

 

But it doesn't work, i have all the textfield invisible!

How can i resolve?