Javascript for text box to auto populate from a check box

[Tara36781991498l]

I have a form with a Yes check box and a No check box. 

When the user checks No, I would like the text box beside it to autopopulate to read "Not Applicable".

When the user checks Yes, I would like the text box to be free flow text entry.

I am stuck on the javascript to accomplish this. Also, does the script go into the properties of the checkbox or into the text box? 

Using Adobe Acrobat X Standard

[Thom Parker · Accepted solution]

To get started read this article:

https://www.pdfscripting.com/public/How-to-write-an-If-statement.cfm

Basically, you want to use the MouseUp action to run a script that will set the value of the text field when checked, and make it read only,  but when uncheck, clear the field and make it not readonly.

var oTxtFld = this.getFeild("TextField");

if(event.target.value == "Off")

{//Unchecked

     oTxtFld.readonly = false;

     oTxtFld.value = "";

}

else

{

     oTxtFld.readonly = true;

     oTxtFld.value = "Not Applicable";

}